High Temperature Issue While Driving

[Jlaa]

@gsxr
I have several friends who own E500's and they don't see temp. readings as high as mine in summer. Am receiving the OBD1 code reader in the next few days and am hoping this will shed some light on the issue and point us in some direction. Otherwise am puzzled and have reached a dead end.
Checked the vacuum lines to the EZL. They are fine. One line to the EGR was found defective and has been repaired. Drove the car with a MAF from another car. No impact at all. Checked ignition timing. Also in spec.
Removed thermostat and drove the car with distilled water only and no coolant for better thermal transfer. Also no change.
No symptoms of head gasket failure or water pump issues.

@Gullwing —- you mention several times that you seem to be at a dead end and that the high temps are inconsistent… sometimes at idle the temps come back down to 85-90C and sometimes they stay elevated. As well your troubleshooting has seemed to indicate airflow is working and the sensors are accurate.

Could the issue be that coolant is not flowing consistently? Could it be that the water pump impeller is slipping on its shaft? This is a common issue with BMW M50 engines of the same era. A water pump w an intermittently slipping impeller would not leak coolant nor would it necessarily have bearing noise.

 

[Gullwing]

@Jlaa
Thank you very much for the valuable input. It is definitely a point we can look at. Does anyone know if the water pumps are known to have any issues? Anyone experienced a water pump failure?
I have no leak or bearing noise so am wondering if it is worth going down that route to open up the water pump?
My water pump has not been replaced as long as I have the car which is a long time.
While being there could of course replace it but would rather not do things which are not necessary.

 

[Jlaa]

@Jlaa

I have no leak or bearing noise so am wondering if it is worth going down that route to open up the water pump?

I thought you were at a dead end? If you are not at a troubleshooting dead end, what other avenues are you investigating? Anyways, if you do undertake this effort, it might make sense to replace the crankshaft seal at the same time with little marginal effort.

 

[gsxr]

@Gullwing, based on a report in a different thread, have you confirmed that vacuum is present at the EZL? And when the vacuum hose is connected / disconnected, the idle speed changes briefly?

Someone else mentioned that engine temps dropped noticeably when this vacuum line was repaired, and the engine ran hot without the vacuum signal to the EZL.

:

 

[Gullwing]

@gsxr
Thank you for the additional hint regarding vacuum to the EZL. We had checked this previously when carrying out the troubleshooting and noted that the vacuum lines are intact and vacuum reaches the EZL. The idle speed also changes briefly when vacuum hose is disconnected/connected.

I now got the blink code reader and we read out all the relevant pins. No faults recorded except on socket number 8 which is the Base Module.
We got error 5 which is 'Maximum permissible temperature in module box exceeded' and error 17 which is 'Voltage supply for module box blower motor interrupted'.
I don't think these have anything to do with the engine running hot or could there be a connection? I was hoping we would get some other codes which would point us in the right direction.

 

[gerryvz]

Those are common, throwaway codes that don't have any relevance to your issue, correct.

 

[gsxr]

@195910 - any ideas on this one?

 

[Gullwing]

@gsxr
As a next step, decided to change the oxygen sensor. Ordered that now and will see if that changes anything considering it hasn't been changed before. If it is faulty would have probably gotten a code during the readout but lets see.
If that doesn't change anything, will look at the water pump and have that opened to check. That is the last component in the cooling system I haven't looked at.
Have no other ideas. There are no symptoms pointing to a head gasket issue.

 

[Gullwing]

Wanted to give you guys an update. Replaced the oxygen sensor and also all 3 cylinder head temp. sensors (for engine management, temp. gauge and electric fans). There is still no change and problem still persists.
Having analyzed the situation once again, I notice that the temperature climbs above 100 Deg. C. up to 110 when the engine is under load. This means driving at normal speed or even when stopped and keeping the engine revved on 2.500-3.000 rpm.
The electric cooling fans at high speed and the fan clutch roaring does not bring the temp. below 100 Deg. C. In the contrary it climbs.
Ambient temp. also not too high at 33 Deg. C. (91F). If I let the car idle for about 10 mins. the temp. slowly drops below the 100 deg. C line. Once there is load again temp. climbs and is quickly on 100 Deg. C. and above again. Have the cooling harness installed so electric fans are on continuously at high speed as temp. never drops low enough. So clearly something is not right. At these ambients the car should run at 90-95 Deg. C and not 100 or above . It should not need the electric cooling fans on high speed while driving and fan clutch plus air flow should be able to cool the engine adequately to remain at that temp.
Have changed everything in the cooling system except the water pump. Could this be the culprit?
Am now thinking that problem can only be corrosion (blockage) in the cylinder head or a head gasket issue.
Do you guys have any other ideas before we decide to open up the engine?
A point I mentioned earlier is that this problem started after replacing the MAF with a reconditioned unit. The MAF had to be replaced as it was faulty and car was running extremely rich, cut out, hesitated etc. So the faulty MAF and running rich could have masked the temp. issue.
Could the new MAF cause hot running?

 

[nocfn]

Have you ever performed the MB Citric flush? Or drained the coolant from the block drains along with the radiator?

 

[Gullwing]

@nocfn
No haven't done a Citric flush and haven't drained the coolant from the block. Radiator is new.

 

[gsxr]

I can't remember if you've done this yet, but have you checked live data to confirm the new/reconditioned MAF is providing accurate values? You'd need to look at the airflow in kg/hr on HHT-Win at 1000, 2000, and 3000rpm to get a rough idea if it's working properly. I expect it is, but since you are running out of possibilities, it wouldn't hurt to double-check.

Otherwise I'd consider the acid flush (PITA, as it requires multiple rinses to remove the acid, and you can't put cold water in a hot engine)... and finally a new water pump, although I'd be surprised if that was the culprit.

When it's at 105-110°C, have you measured the coolant temperature at the radiator inlet hose, vs outlet hose? If the radiator inlet hose temp is lower than engine temp, that may indicate a flow problem (water pump). The radiator inlet should be very close to engine temp; the outlet should be lower.

ALSO - is there any chance someone modified the water pump at the thermostat seating area, thinking they were "improving" cooling? The factory design has the t-stat close off the small hole when fully opened, this prevents hot coolant from re-entering the block. When the t-stat is fully open and this port is blocked, it should force all hot coolant out the top to the radiator. The M119 FSM doesn't show a circuit diagram but if you click here, the M104 diagram is similar in theory.

 

[Gullwing]

@gsxr
An important point to note is that after parking the car last night (temp. at around 110 Deg. C) I found a puddle of coolant under the car
this morning in the area of the expansion tank. Very interesting was that when I opened the expansion tank cap there was a huge release of pressure and it splashed out some coolant (with engine fully cold not started since last night).

 

[gsxr]

At high temps (like 110°C), it's normal for the expansion tank to be full, and allow some coolant out the overflow hose to the catch tank located inside the passenger fender. When the system cools down, it will automatically suck the overflow back into the system.

Pressure in the system at high temps is also normal - but you should avoid opening it when above 60-70°C, or you'll lose some coolant. The level should be checked only when cold and should be at the tank/reservoir seam.

Once the level is corrected, see if you can determine the source of the leak. There should never be coolant on the ground unless the overflow tank in the fender is full (it should be empty, or near empty).

 

[Gullwing]

@gsxr
Thanks for your inputs. I was more concerned about the fact that when opening the reservoir cap this morning with a fully cooled down engine (ran the night before) there was a huge release of pressure and it splashed out some coolant.

 

[gsxr]

AH, sorry, I didn't understand that... if you had high pressure in the system when COLD, this is not normal!!

It might be time to test for exhaust gasses in the cooling system, if that has not been done yet:

Amazon.com

 

[Gullwing]

@gsxr
Yes there was high pressure when cold. So you are tipping on head gasket failure? Thanks for the link to the test kit. Will get that ordered.
Should it turn out to be the case, what do you think of head gasket repair additives which are added to the coolant? I heard that some of them work-worth a try or not?
Tested the car again tonight. Could have driven around in the parking for an hour - temp stayed steady at 90-95. Once I took it out on the road driving 60-80 Km/h with some stop and go temp started to climb to 100 and then again to 105-110 once I reached the parking again.
So this confirms that temp. climbs once the engine is under minor load.

 

[gsxr]

High pressure in the M119 cooling system when cold is not normal, and assuming you can repeat this symptom, it's not a good sign. And yes, my next suspicion would be head gaskets. This is a fairly expensive job due to many hours of labor, and although the head gaskets are not expensive, there's a lot of "while you are in there" parts which add up fast. In the USA this would be a few thousand USD at most shops.

There are some liquid head gasket repair additives that might work, however I'm not sure how well these would hold up in high ambient temps and/or heavy load. I would have low expectations, and consider this a temporary solution (if it does anything), not a permanent fix.

IIRC, this is the sealant @jhodg5ck recommended?

https://smile.amazon.com/Bars-HG-1-Blown-Gasket-Repair/dp/B003RGIWO0/

 

[Gullwing]

@gsxr
Thank you for all the information. In case it does turn out to be a head gasket issue, I might try one of the liquid head gasket repair additives as I have nothing to loose. I was thinking to try the K-Seal Ultimate product.
For the M119 head gasket replacement job, does the engine have to be taken out/dropped or can this work be performed with engine in?

 

[gsxr]

The job can be done with the engine in the car. However... if there is ANY excuse to pull the engine, the job will be much easier with the engine out, and then you can also re-seal the transmission, clean the engine compartment, and do other stuff which is otherwise difficult or impossible with the engine in place.

 

[emerydc8]

@gsxr
Thank you for all the information. In case it does turn out to be a head gasket issue, I might try one of the liquid head gasket repair additives as I have nothing to loose. I was thinking to try the K-Seal Ultimate product.
For the M119 head gasket replacement job, does the engine have to be taken out/dropped or can this work be performed with engine in?

I used the aforementioned Bar's head gasket sealant on my 1995 E420 over five years ago and it's still holding. It gets really hot out here in Tucson and every summer has been a concern for me. I haven't experienced any notable coolant loss, but I also don't make a habit of pushing the limits on this car. I keep an extra bottle in the trunk just in case it starts leaking again, but I've been pretty lucky. It's good stuff.

 

[Gullwing]

This was opening the expansion tank cap this morning with fully cold engine. So same as yesterday. Even though there was coolant under the car again in the expansion tank area and coolant splashed out again today when opening, the level in the expansion tank is still normal.
Does this point to a blockage of some sort?
Did not test for exhaust gases in the cooling system yet.

 

[gsxr]

Yikes. If that's fully cold... something ain't right. I would test for exhaust gas in the cooling system next.

 

[Sam SL]

+1 on testing for exhaust gas and bad head gasket.

 

[Gullwing]

Have done several tests with the CO2 tester at the expansion tank with both hot and cold engine. Came out negative. Also did a cylinder leak down test. All normal.

 

[Gullwing]

Removed the water pump for inspection. All fine. So reason is not the water pump. Can rule that out. Removed the radiator to inspect (even though new) and also sent the original radiator for inspection and service.
Reason now can only be a blockage somewhere as the pressure buildup and air pocket is caused by something and there clearly must be a circulation issue. Ordered the Mercedes citric acid flush to try that as well. Otherwise we have no more ideas.

 

[gsxr]

While I've never heard of this on an M119... some OM60x engines are known to have high pressure in the cooling system when cold, due to cracked in the cylinder head. The cracks don't allow water & oil to mix, and may not have exhaust gasses in the cooling system, but the cooling system pressurizes abnormally when the engine is under load and the high combustion chamber pressures go through the crack into the coolant.

This would be very very unusual for an M119, but if you run out of options, it's one of the few remaining possibilities. Unfortunately the heads have to be removed for inspection ($$$$) to determine if this may be the cause.

 

[Gullwing]

@gsxr
Now the water pump has been opened would you recommend that I change it with a reconditioned original unit or fix the old one back?
Impeller is fine and no drastic signs of cavitation or wear.

 

[gsxr]

@gsxr
Now the water pump has been opened would you recommend that I change it with a reconditioned original unit or fix the old one back?
Impeller is fine and no drastic signs of cavitation or wear.

If it's the original from the early 1990's... I'd spring for a new OE (probably rebuilt) pump. Cheap insurance after nearly 30 years. Cost was quite reasonable (~$250 USD?) last I checked. I'd be nervous about aftermarket pumps though. Lots of labor to R&R the pump, labor may cost more than the pump itself. Not a fun job.

 

[gerryvz]

If it's the original from the early 1990's... I'd spring for a new OE (probably rebuilt) pump. Cheap insurance after nearly 30 years. Cost was quite reasonable (~$250 USD?) last I checked. I'd be nervous about aftermarket pumps though. Lots of labor to R&R the pump, labor may cost more than the pump itself. Not a fun job.

I installed an aftermarket GRAF pump last year as part of my top-end refresh. The casting was not quite as crisp/sharp as the original factory pump's was, but it was fully funtional and fit just fine. It has worked just fine and operates identically to the original pump (which I saved, and was working fine). I have around 3,500 miles on the pump since it was installed.

 

[Jlaa]

I installed an aftermarket GRAF pump last year as part of my top-end refresh. The casting was not quite as crisp/sharp as the original factory pump's was, but it was fully funtional and fit just fine. It has worked just fine and operates identically to the original pump (which I saved, and was working fine). I have around 3,500 miles on the pump since it was installed.

Good to hear. I remember @jhodg5ck saying something about using a feeler gauge to measure…….. something ………. on GRAF pumps before installing. Did you do that and do you remember what that measurement was for? I can’t find his comment and I have that same GRAF pump on the shelf purchased from FCP when it was on sale for some absurdly low price.

 

[gerryvz]

Nope, I didn't. I compared it to the existing factory pump, and then installed it.

 

[Jlaa]

Ah, I found jono's comment. Putting it here too so I can find it when I get around to it.

FWIW, I stick w/ the Genuine pumps. If you do go aftermarket take the time to check the back spacing of the impeller to the housing. I find it varies quite a bit from pump to pump. Most are in spec but Some are not and that can lead to some nasty frustration when you put a new pump in and temps do weird things subsequently.

oh, you'll want to have a hydraulic press around to squeeze that impeller down..levering it up can be a bit tricky..just try to get a Solid purchase on two sides when raising it up.

jono

 

[gsxr]

OE/dealer rebuilt pumps are ~$150 with core exchange, or ~$225 outright if you don't have a core.

Looks like Graf is <$100.

If Jono is implying that OE doesn't have the impeller spacing concern, that might be enough to justify the additional cost.

 

[Kyiv]

I've had a Graf coolant pump on for 3 years and over 20k miles. So far, so good

 

[Gullwing]

Hi guys,

Just an update. The problem is still there. Today when we went for another test drive a fault came up. The ASR light came on and there was no throttle response. Fault code we read out was 30 communication error. Does this point to a faulty throttle body wiring harness? I know that the harness for the electronic throttle actuator are an additional weakness on these cars.
Now my most important question: Could a faulty harness be the cause for my temperature issues or is there no connection whatsoever and can be ruled out? Thanks.

 

[gsxr]

ASR module code 30 is a "generic" code stored pretty much every time limp mode is triggered. Check the codes on E-GAS (EFP), pin #7 and see what shows up there. ASR code 30 is a useless code, unfortunately.

The traction (ASR) and throttle control (E-GAS / EFP) systems can not, AFAIK, affect engine temps in any way - not even if the harnesses are bad. Fuel mixture is controlled by LH and EZL, these could affect engine temps if something is awry.

Bottom line, the ASR fault / limp mode should be an entirely separate issue from the hot running problem.

 

[Gullwing]

@gsxr
Thank you for the helpful advice. We just checked the codes on pin #7 and it threw out the following codes: 2, 3 and 14. Any guidance on what to look at first?
Since we can rule out the cooling system I think there is no harm to look at the EZL or LH as potential causes for the high engine temps.
There is a R129 SL500 in the workshop with the same engine. Are the EZL and LH interchangeable? In case yes there is no harm to swap the parts and see if there is any change with regard to the engine temp.
We did not get any fault codes on the EZL or LH though. Could there still be a fault with one of them anyway?

 

[gsxr]

E-GAS codes 2 & 3 have a lot of possible faults, see below. You need a digital scanner to narrow it down; although all the codes for #3 indicate a problem with the ETA. #14 is Closed throttle position switch (S29/3) however this isn't necessarily a bad switch, if the throttle linkage is mis-adjusted you can get the same code.

If the SL500 has an M119.972 engine, yes the LH and EZL are interchangeable. Neither should affect operating temps but there's no harm in trying to see what happens. It's unlikely your LH or EZL are faulty if there are no codes, and the car otherwise runs perfectly except for the high coolant temps.

 

[Gullwing]

@gsxr
Today we performed the citric acid flush. The flush water which came out was not very discolored. Tomorrow another test drive to see if that
changed anything. I don't think so honestly.
Today another warning light came on - Exh. Temp. I did not get any warning lights as long as I own the car which Is many years. Yesterday ASR and today Exh. Temp. We reset the ASR fault codes and the ASR light came on again later today and it went into limp.
This car is really starting to drive me up the wall and I am beginning to lose my patience. It is having a laugh. Am close to driving it into the sea.
Exh. Temp. light usually points at a clogged cat or wrong timing which can of course cause hot running or can screw up the air/fuel mixture. So could be that we were looking in the wrong direction all this time with cooling system and engine internals. We can now rule out the cooling system and head gasket.
So could be the issue was electrical like timing or air/fuel mixture all along. Tomorrow will also again read out pin# 17 for the EZL and also pin# 4 and pin# 8. Maybe we get some faults this time after the Exh. Temp. warning light today.
We didn't investigate EZL or LH any further since so far we didn't get any faults.
Any thoughts or anything else we should check?
As a last option will also swap the EZL with the one in the R129 SL500 and see if that changes anything.

 

[gsxr]

The EXH TEMP warning is worth looking into. Plugged catalysts could possibly cause abnormally high temps.

I had been assuming power was normal, however if you don't have a reference point to know what "normal" is, this isn't always easy to check. Cats can be tested with an exhaust backpressure gauge but the car must be driven at full throttle under load while monitoring the gauge. Can't be tested with the car stationary, unless it's on a dyno.

EDIT: I already forgot about the abnormal pressure in the cooling system. I think the catalysts are probably ok, but this should be tested since you have the EXH TEMP warning.

 

[robm.UK]

@Gullwing
You might have multiple problems. Fuelling and coolant flow.

1) Fuelling.

Did you unplug the MAF like @gsxr recommended? Any difference?

Have you looked at the spark plugs? A lean running engine can cause the engine temperature to increase especially under load, but if this is the case the ceramic nose of the spark plugs would be bright white in colour, not the normal light brown. Post a photo of one of your spark plugs.

2) Coolant flow

High pressure in the coolant can be due to a failing head gasket as gsxr said, but it can also be due to a partially blocked radiator.

I know others have had similar overheating and high pressure problems on M119s from accidentally mixing IAT (OE glycol based) with OAT antifreeze. The M119 is very tricky to flush. You said you used Petronas antifreeze. I assume this was OAT because I can’t find Petronas IAT antifreeze. Correct? At the factory the antifreeze was IAT (glycol based) and I assume that IAT was used in the previous tri-annual services? So, was OAT introduced last December when the shop changed your coolant? Did they drain the rad and the block on both sides with the heater control on and fully open and the radiator cap removed? Personally I won’t let OAT or HOAT anywhere near my M119 because when IAT and OAT mixes it can often form globs of gel in the system. I know of one very long post at BW forum where this occurred and partially blocked a brand new Behr radiator. The globs can stay in the block and heater matrix even after flushing and then get dislodged and block the tiny channels in the radiator. Worst still IAT and OAT mix in your rad and form the gel.

Hot running V8 conundrum

The video at the end of the thread demonstrates the partially blocked radiator.

 

[gsxr]

MB tech article on antifreeze at link below, for anyone interested:

https://www.w124performance.com/docs/mb/other/antifreeze_article.pdf

Note that G-05 and G-48 are both considered HOAT. The old green Prestone from back in the 20th century was IAT.

If an OAT antifreeze had been used after IAT (or vice-versa) at any point, that could have caused some issues.

 

[JC220]

MB tech article on antifreeze at link below, for anyone interested:

https://www.w124performance.com/docs/mb/other/antifreeze_article.pdf

Note that G-05 and G-48 are both considered HOAT. The old green Prestone from back in the 20th century was IAT.

If an OAT antifreeze had been used after IAT (or vice-versa) at any point, that could have caused some issues.

Thanks for the white paper Dave makes good reading

 

[robm.UK]

^^^ ditto

 

[robm.UK]

@Gullwing
I meant to add that the gel in the expansion tank in your photo from post #44 could be from a reaction between IAT and OAT antifreeze. (See my post #142).

What can be one? I have always been dubious over the effectiveness of flushing a radiator once it’s partially blocked with this gel, which is sticky and hard to shift. Even with a power flush the water can flow around the blocked channels easily.

There is a way to check the radiator for partial blockage. With the engine at operating temperature, use a thermal imaging camera and take temperature readings across the heater core. If there is a cooler spot in the middle or part of the radiator, it is probably blocked.

 

[Gullwing]

@gsxr
@robm.UK
Thank you for all the valuable advice. Wanted to give you guys the latest update:

ASR Light & Limp Mode:
Yesterday we were able to reset the fault codes on pin #7 and ASR stayed off for a while. Today ASR light came back on again and car went into
limp mode before being able to go on a test drive. Today we only got fault codes 2 and 3 on pin #7. Yesterday we got fault code 14 in addition. No faults on pin # 4, 8 and 17. Resetting the codes didn't work today as ASR light came straight back on immediately after starting.
Guess what....a simple diagnosis by moving around the wiring harness of the ETA resulted in the ASR light going out. Moving the wiring harness again made the ASR light come back on. So the ASR issue definitely points to a ETA wiring harness issue which I heard is a common problem if it hasn't been addressed yet and is advisable to be done. I have not done anything on the ETA since I own the car which is many years.
The electrician will inspect the wiring on Saturday and will see if anything can be repaired.

Exh. Temp. Light:
The Exh. Temp. light stays on even after a cold start so this points to an issue with the sensor, wiring or connection. Yesterday the light also went out after a while. Today it stayed on. There is not much information to be found on this but we suspect the sensor is wired directly and does not feed to the LH or any other control module so hence it should not affect running i.e. timing or fuel/air mixture. Correct me if I am wrong. We still need to verify this.

Temp. Issue:
We replaced the new Behr radiator with the old original one after having it serviced and tested. Now there was no more pressure when opening the expansion tank cap when cold. Interesting development.
We weren't able to test drive the car yet after the citric acid flush due to the ASR limp mode.
So we are yet to find out if that changed anything. What we could find out though is that before ASR/limp mode came back on we could idle the
car and keep the accelerator on around 2.500 and 3.000 RPM for about 15 mins. and the temp. stayed steady on 90 Degrees and did not climb.
Before you could watch the temp. needle climb fast and immediately to 100 and then 110 when doing this as soon as the engine was under load.
This is a good sign. Too early though to say that we nailed the issue since a proper test drive will tell us for sure.

 

[Gullwing]

@gsxr
@robm.UK

Just wanted to update you guys with what we found in the ETA wiring harness. All the wiring has disintegrated and the insulation has pulverized.
Bare wires touching each other. Am surprised the car still ran as good as it did and that we didn't get the ASR fault any earlier.
Will probably notice a huge difference though once this has been sorted.
Do you recommend any other parts to be changed while doing this?

 

[gerryvz]

Not a surprise to hear and see this. ALL owners should get their ETAs professionally rebuilt (not just the wiring goes bad). Been saying this for years.

Be sure to send your ETA to Don Roden in Alabama. Plenty of info here on the forum about him and his stellar work.

 

[Gullwing]

@gsxr
Is there a thermostat with a lower opening temp. available? My thermostat is the earlier version without the housing.
Is there a part number?
If not am thinking to undertake the thermostat modification by drilling two holes. Is there a photo somewhere showing where the holes need to
be drilled? Thanks.