Huge Coolant loss

[Fakemozz]

Hello everyone

i bought an 1991 euro model 500se w140 with m119.970 engine that didn't run in the past 15 years

rebuilt the engine Harness changed rotors and caps and verified the insulators; all good

the car runs a bit shaky but it runs and revs okay-ish

Now to my problem

Huge white smoke very dense and the coolant reservoir looses nearly a gallon in less than 10 minutes of idling with some small revs

the temp stays approx at 170 degrees

is it a head gasket ?

is it possible that the intake water passage leak into the cylinders ?

i would love to try a sealant but if its just the intake gasket i can and prefer changing it

but a gallon in 10 minutes i never see such huge burning

what can i test to eliminate the HG

i checked compression i got 170psi on all 8 cylinders

Thanks for helping
and sorry for my bad english im from France

Have a nice day

 

[gsxr]

I wouldn't try sealant if you are losing 1 gallon in 10 minutes.

Do all 8 spark plugs look identical? If 1 or 2 appear different than the others, those are probably the cylinders consuming the coolant. Might help narrow your search. You could also try using a borescope/camera in each cylinder while pressurizing the cooling system to see which cylinder(s) have coolant appear. Normal compression on all cylinders is a good sign.

Not sure you'll be able to tell what's going on without at least removing the intake manifold... if the intake gaskets are good, pretty likely you'll need to pull the heads.

 

[Fakemozz]

Thanks ! I will buy a pressure tester as i already have a borescope Its frustrating since the compression are near to perfect

Will report back

 

[JC220]

What Dave said

Plus you can buy inexpensive head gasket coolant "sniffer" kits on ebay and the likes. Place the tester over the coolant header tank opening and use the coloured test fluid. Run engine and allow to warm up. If combustion gases are present within the coolant system the test fluid will change colour.

 

[Fakemozz]

Im good for replacing the hg
I borescope and saw a lot of water and when I press on the Upper Radiator Hose a big water squirt comes from the Head gasket
I will See the timing First and Then replace Both Head gasket and chain of its out of spec
Thanks for helping Hope I will get it done soon

 

[JC220]

Im good for replacing the hg
I borescope and saw a lot of water and when I press on the Upper Radiator Hose a big water squirt comes from the Head gasket
I will See the timing First and Then replace Both Head gasket and chain of its out of spec
Thanks for helping Hope I will get it done soon

Great stuff.

Don't forget to budget at least 1x grand for the associated gaskets and ancillary parts that will crumble during the job.