Just bought my 92 300 sl and blew the head gasket. The local ( non mercedes) repair shop I took it to replaced the gasket and had the head machined. Since the repair, the temp guage is reading between 100 and 120. It does not go any higher and the car does not seem to be overheating. Formerly, the temperture ran at about 80. Please let me know.

 

I have no experience with your particular vehicle, but after a blown head gasket, it is common to need a new engine temp sensor(s). They are designed to operate in a certain range of temps and pressures while in contact with coolant. Contact with high pressure steam and/or combustion gasses can and will damage them.

 

Hello

I can share my own experience, which may worry you, or even mislead you... because I'm sure there are lots of different reasons why this is happening.

My 500SL had a warning light on the dash, and overheating, and I called my garage who advised me that they couldn't tell me exactly what the problem was unless the car failed, as the car was not so easy to diagnose with it being 12 years old. The head was pressure tested and they couldn't find a problem. So I let it fail, and the mechanic came out and pressure tested the head for me again, and found one side of the engine had failed, and I had to have the full head gasket set replaced, and skimmed.

The important thing to note here is that the pressure test only tests the heads! (I think... someone tell me if I'm wrong).

When the engine was put back together it didn't solve the problem. I was forced to have the engine re-manufactured, and when it was taken apart it was found that the head skim hadn't fully solved the problem of the seal, as there was not sufficient contact with the block, due to a slight bump at the contact point. The engineer at the specialist engine place showed me that when the head had been put back on the gasket should compress all around to create the seal, and it didn't because of slight bumps at the contact point.

Water had ingressed in places which were separate from the head gasket, and over a period of time had generated permanent piston damge, (one of the pistons was actually bent severely, and none of us could believe that the engine turned over at all!). We had to replace all the pistons with new ones, and have the cylinders relined, skim the block, replace the gasket set (again), and ... well, it's a long list, and was very expensive.

I guess the main thing to bear in mind is that replacing the gasket set, and skimming the heads may not necessarily solve your problem. You should have a fully qualified engineer look at the engine, and find out exactly what made the gasket fail in the first place. I don't blame my garage for not solving the problem by the way, it's just that I should really have taken the car to a specialist engineer. But I didn't have any experience, and my garage, for the most part will only do what I pay them to do.

On a philosophical note I now have a practically brand new engine, which has prompted me to replace the soft top, and slap some big alloys on it... and it should last me another 100,000 miles. But it was a very expensive exercise. The engine alone has cost £5000 to repair.... which in todays US money is about $8700!

By the way I am looking for a panoramic roof if anyone has one, my car is 1991 500SL in blue. Thanks very much.

 

Hey... thanks for the informative update. The heads on the car was pitted (I was told that not changing the coolant had caused that) Now the car runs at a constant temp of about 90 degrees. My 1996 E320 runs at a constant 80. Can someone advise what's a good reading for the 300SL