Deadbolt9009

I purchased a 1991 190E 2.6 in June 2021 with approximately 196,000 miles. Engine performed very strongly during test drives which prompted me to buy it but was purchased as is where is based on the negotiated price. Previous owner said head gasket had never been replaced to his knowledge. Have put over 10,000 miles on it with full knowledge that it does consume oil and coolant. I’m ok with that as it has been very reliable. Replaced tires, engine oil/filter, transmission flush and new fluid/filter, spark plugs and Cold start valve and relay. Runs great. QUESTION, I now suspect head gasket is failing due to increase of coolant use and I can also see coolant on engine block exhaust side so would there be any advantage to having the cylinder head bolts re-torqued if cylinder head gasket is failing or would it be a waste of time/labor?

chassis

Waste of time and labor and risks stripping threads in either the block or the bolts.

Do the proper job and replace the cylinder head gasket.

dolucasi

I second that emotion! Once water/oil is seeping the gasket is shot and will do further damage. You could even have head warping if the car overheated in its past history. While you have the head off, you should have it machined (and planed) at a reputable machine shop who knows these engines and have the valve guides replaced as well as valves checked for wear. My head gasket never leaked oil or water when I had the head machined at ~185K miles but the guides were worn.
It is a lot of work but a DIY job (except for the machining which would cost $500-$700 depending on where you live).

The head is torqued to yield and is on already super tight, I suspect >>120 ft-lbs effectively and the bolts actually stretch. So it is advised that the bolts be replaced as well (though this is not mandatory)

Deadbolt9009

Good advise and is the answer I expected. To my knowledge based on what previous owner told me the engine has never overheated but I will now plan to pull the head either by myself, which I can do but may just job out due to other factors…like not enough time in the day and still be responsible for day to day operations. Will have head planed and valve guides replaced as well as new head bolts and anything else that needs replaced/renewed. Thanks all for your advise!

190Efan

I totally agree with all of the previous advise. FYI, the 6 cylinder M103 engine which is the engine your car has, is notorious for head gasket failure. Be sure to keep up with all regular maintenance and you'll have a reliable car for years to come. BTW, welcome to the 190E universe. A picture of your 2.6 would be nice when you get the chance. You might also want to invest in a Haynes manual for your car as a good reference. They're not that expensive, about $25.00 at the Haynes website.

Deadbolt9009

Thanks for the advise from all. Head gasket replacement is now on my bucket list of to do items for 2022!


My 1991 W201 190E 2.6 at 206,000 miles

bicylindrico

They fail due to corrosion. Also, do not let the engine sit if you know the gasket is allowing coolant to leak into the engine. The coolant will cause rust in the affected cylinder and you will need more than a head gasket when it drinks a quart of oil a day.

190Efan

Driving a car with a leaking head gasket can also cause serious and expensive engine damage as well.

dolucasi

I should also add that besides the gasket corrosion, the iron cylinder block mating surface also corrodes over time and develops some surface pitting. I was advised by my machine shop to block sand the bottom mating surface with a 100-200 grit sand paper. I did that and it was a lot of work but at least I know the new gasket went in to a clean surface on both sides. All the water, oil and bolt holes need to be plugged for this obviously.

355190e26

+1, proper prep of the block is key for a long lasting job.
I went with a little different approach and put marvel mystery oil in the cylinders as well as on the iron block. Then I hit it w/ various Scotchbrite drill wheels until the surface looked flawless. Probably spent at least 4 hrs over 2 days on this. Done at least 3 M103 head gaskets this method and all are still working perfect.