Is a head gasket failure common on an M119?

[alabbasi]

This is for my 98 SL500. I drove it to my shop which is about 60 miles away from the house and the car behaved flawlessly. When I got there it gave me a little bit of a hard time starting and then I saw steam from the exhaust. Coolant light also tripped and coolant was low. I don't see much information on HG failures on M119's so I'm wondering if this is what it is or if there's something else that might be going on?

I'll dig more into it when I get back from my trip.

 

[R129 UK]

How many miles has it done?

I wouldn't say it was a common issue compared to M104s etc. which seem to need doing at or around 100K miles.

Obviously check for oil in the coolant or coolant in the oil or bubbles etc.

 

[alabbasi]

It's got right around 77,000 miles. No oil in the coolant or obvious signs of it but there's plenty of steam as you can see in the picture. I'll pull the plugs and use an inspection camera in it when i get back.

 

[gsxr]

...I saw steam from the exhaust. Coolant light also tripped and coolant was low. I don't see much information on HG failures on M119's so I'm wondering if this is what it is or if there's something else that might be going on?

Head gasket failure on the M119 is CRAZY rare. Like, almost unheard of. It can and does happen, but the vast majority of M119's go to their grave with the original head gaskets. I know of one that had a lower radiator hose fail, lost all coolant, was continued to be driven at freeway speeds until the temp pegged and the engine shut off (!!!), and still did not blow the head gaskets! (That was clearly an anomaly, but after cleaning up the oil around the spark plugs and fixing the cooling system, that engine ran normally and was back in service for tens of thousands of miles afterwards. This was an early closed-deck engine, btw.

Anyway. Start with the borescope, check the plugs, and pressure test the cooling system to start with.

I don't know if the later open-deck engines are more prone to gasket issues or not. @Klink?

 

[R129 UK]

I don't know if the later open-deck engines are more prone to gasket issues or not?

Not at all that I am aware of.

 

[emerydc8]

Out of curiosity, could a leaking intake manifold cause this?

 

[gsxr]

Out of curiosity, could a leaking intake manifold cause this?

YES. It's not common, but a failed intake manifold gasket can allow coolant to enter the intake tract, I believe at the rear cylinder intake ports (4 and/or 8). This would result in smoke out the exhaust and loss of coolant.

Good call, Jon!

 

[gerryvz]

Intake manifold gasket failures are much more common than head gasket failures on the M119. That said, both types of failures are very rare.

 

[alabbasi]

Thanks all. I was under the assumption that the intake leaks are external and won't cause water to leak into the cylinders.

I can start by pulling the intake and seeing where where are.

 

[alabbasi]

I think I have some bad news. I've been away for a couple of weeks but managed to get back to the shop today.
I pulled all the plugs and found cylinder #5 was full of coolant (relative to where the piston was). So much so that the engine acted like it was locked up.

Here's a video where you can see coolant blow out of the cylinder once I turned it over.

i'm going to drain the coolant to prevent it from locking up again and and spray some WD 40 in the cylinder. Well that sucks!

 

[gsxr]

There's a coolant channel next to the #5 inlet port. There's still a chance the leak was at the intake gasket, not the head gasket. You'll need to pull the intake to find out. I'd consider pulling the #5 injector and using a borescope to watch while pressurizing the cooling system...

 

[alabbasi]

Thanks Dave I"m game for that. The intake has to come off for the head to come off.

 

[alabbasi]

I started the process of removing the intake, I took the fuel rail off first so that I can get it and the wiring out of the way but I ran into some problems with a few of the intake bolts that are not budging. The one right by cylinder #4 and the one behind cylinder # 4 as well as on the the long ones by cylinder # 1 in the front.

I feel like if I torque on them too much they will snap. Any recommendation here?

 

[JC220]

I started the process of removing the intake, I took the fuel rail off first so that I can get it and the wiring out of the way but I ran into some problems with a few of the intake bolts that are not budging. The one right by cylinder #4 and the one behind cylinder # 4 as well as on the the long ones by cylinder # 1 in the front.

I feel like if I torque on them too much they will snap. Any recommendation here?

For bolts like that Id try to get some heat into it with a torch. The head will dissipate the heat fast but better than nothing.

Then use a battery impact gun turned low and hammer on it for a while whilst turning up the power until it comes loose.

 

[190EVAN]

Yeah if it’s been sitting for long a bit of heat can help loosen things up. If the car was previously ran to temp, usually I get by simply by striking the intake manifold bolts with a hammer using a long allen socket as a punch.

Honestly I do it mindlessly at this point whenever I work on M117’s or M119’s regardless of if a bolt is giving me an hard time and rarely run into issues with stripping threads or them being seized up.

I have rebuilt a good number of M119’s and have never diagnosed a failed head gasket. Now if user error caused a head gasket failure that’s a different story, but from my experience you can really neglect an M119 and the head gasket usually isn’t the bottleneck. If the car was driven in a hot area with a failed fan clutch and inoperative Auxiliary fans I could see it boiling and causing a head gasket failure.

If you haven’t removed an M119 intake manifold before, when you do you will see a pronounced rubber seal path around where the intake manifold seals the coolant passage ways. There are bad mechanics out there who will re-use an intake manifold gasket (lord knows why, they are so cheap) and this would most certainly cause what you are seeing.

The coolant passage ways sealed by the intake manifold gaskets would show this issue in primarily cylinders 1, 4, 5, and 8 as they are the nearest intake ports to the passageways.

Good luck, if I were you, I would simply pressurize the cooling system and look for where fluid is leaking from, or grab a leakdown tester and pressurize the cylinders. This will also give you an idea of the health of the engine should you decide to tear it down.

 

[alabbasi]

Thank you both. I'll try some heat tomorrow. I try not to be too hard on my cars (except the CDI which I drive like I stole).

 

[190EVAN]

Also, If you are removing the intake manifold this would be a great time to split it and replace the donut seals between the intake halves. They become a bit hardened after 27 years and now is the time to do them.

 

[Klink]

Head gasket failure on the M119 is CRAZY rare. Like, almost unheard of. It can and does happen, but the vast majority of M119's go to their grave with the original head gaskets. I know of one that had a lower radiator hose fail, lost all coolant, was continued to be driven at freeway speeds until the temp pegged and the engine shut off (!!!), and still did not blow the head gaskets! (That was clearly an anomaly, but after cleaning up the oil around the spark plugs and fixing the cooling system, that engine ran normally and was back in service for tens of thousands of miles afterwards. This was an early closed-deck engine, btw.

Anyway. Start with the borescope, check the plugs, and pressure test the cooling system to start with.

I don't know if the later open-deck engines are more prone to gasket issues or not. @Klink?

I have yet to see the first M119 with a head gasket related defect.

 

[TerryA]

@Klink,
Hi Klink! Nice to see your still out there. Have a great Holiday Season.

 

[alabbasi]

I'm feeling more optimistic now although worried about the intake bolts. Gaskets arrive today. Does anyone know if I can get the plastic plug housings new for the wiring harness (cam adjust plug etc). They're all turning into dust the moment I touch them

 

[R129 UK]

Does anyone know if I can get the plastic plug housings new for the wiring harness (cam adjust plug etc).

Yes you can get replacement connectors, let me dig out the part number.

MA012 545 04 28



GBP prices but probably about the same amount in US$

 

[alabbasi]

Thank you!

 

[alabbasi]

Thank you!

 

[alabbasi]

Looks pretty definitive

 

[R129 UK]

I just spotted this on FB, no replies yet.

 

[JC220]

I just spotted this on FB, no replies yet.

Thats just speculation not a diagnosis. These cars and all petrol cars create exhaust gases which can appear as steam in colder months. Moisture under the oil cap is also normal for a car that has had several cold starts and is not driven for long periods on the road.

 

[R129 UK]

Thats just speculation not a diagnosis. Thess cars and all petrol cars create exhaust gases which can appear as steam in colder months. Moisture under the oil cap is also normal for a car that has had several cold starts and is not driven for long periods on the road.

I totally agree, I saw the post and thought it was pertinent to the discussion here.