Greetings all,

I wonder if I could get a little general info. I bought a 1980 SD with 118k on the odo (which I suspect is way wrong, but it ran well) and I love the car. So much so that I took it to a MB shop and spent a thousand on preventative maint.

Car overheated and is in the shop. They say thermostat and head or head gasket, $2500. I did drive it a little while overheated (I know, dumb, but I thought these things were bulletproof and I spent a lot of money on a 77 BMW before I figured out the gauge was wrong) to see if it was the gauge or not.

Is that about right? Is there anything simple they might have overlooked?

Any simple fixes (pepper in the coolant) or am I stuck with a new head and if I do get a new head can I pretty much forget about the engine for a while?

TIA

Replace the thermostat. A stuck thermo can overheat the coolant and thereby mimic all kinds of trouble. Run some powered radiator/head gasket sealant too. Can't hurt.

This is advice is from a "cheapie" Smudge-Pot Pilot that has maintained (for the most part) his own ride for over fifteen years of its’ twenty-five year life.

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Toblin

'79 300D, "Liesel von Diesel", 235K

I kid proofed the house....but they still get in

No engine is "bullet proof".
Ya might have killed it, pistons sticking to the cylinder walls, blown head gasket, cracked head.
I hope you did not put water in the radiator when it was hot!

The weird thing is it was running just fine (except for that temp needle pointing north thing) the engine didn't seem hot, valve cover was warm, hoses and radiator warm, no steam, no leaks. Thats why I thought it might be the gauge. When I let it cool down and restarted and the bottom hose stayed cool I figured it was the thermostat.

I think I will try just having the thermostat replaced. If it's broke it aint getting broker.

Koop,

If you had no steam, you didn't damage the engine unless you ran it so hot that all the coolant was gone, therefore no steam. If this happened you would have known that the engine was extremly hot.

Why does the mechanic say it needs a new head or gasket? If you do a compression test and all cylinders are about the same, I doubt it needs a new head or gasket.

I would replace the thermostat and see how it starts when cold and how it runs in general before I would remove the head, especially for $2500.

P E H

You can also check the radiator hoses for pressure in the morning after having run the car long enough the nite before to bring it up to operating temp. Hard pressured up hoses generally mean a head or head gasket problem. Coolant loss after the air has all been purged would also be a bad sign. Lots of things to check before going out and spending a lot of money, possibly for a job that is not needed.

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1961 190Db retired
1968 220D/8 325,000
1983 300D 164,150

I agree with PEH, does the mechanic own a sailboat or airplane?

Check the coolant for oil and the oil for coolant. If both appear uncontaminated, replace the thermostat, fill it with fresh orange coolant, start it up and let it run for 20 to 30 minutes. If it does not overheat, runs well, and does nothing scary, you're all set. If it all looks good but the gauge points high I would try a new sending unit.

If the fluids are contaminated, then you could have head gasket or head problems.

I'll bet it is just the thermostat.

Jerry

Why do people on thia forum often say to use orange coolant? That stuff turns to mud before the "green" stuff and costs much more. GM says it goes 5 years or 150,000 miles, NO WAY. I owrk at a dealer and 90% of our cars are GM's, when you open the radiator most of them look as if it were filled with Georgia Clay. The stuff looks disgusting. Just use regular green stuff, especially if your just testing it to see if it works. Besides, anything GM comes up with, I don't want within a mile of my car.
David

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2000 Honda Accord V6 137k miles

1972 300SEL 4.5 98k miles

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I prefer Evans waterless coolant. I would use it in everything if it wasn't so damn expensive.

So I just use it in my best MBs.

P E H

I'm with P.E.H.- Evans Propylene Glycol ...that's the good stuff !

Costs about $20- $25 per gallon !

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Diesel-guy

Coolant... I prefer Zyrex G-05. Aside from genuine Mercedes label stuff, it's the only stuff MB approves.

Don't worry, you're not that bad... I overheated my car a few weeks ago and drove it a few short hops thinking if I could get it going then let it coast to a stop it might "help cool it". Eventually I got my wits and hot-wired the electric fan and let it sit for about an hour with the heater on... much smarter idea.

Mike

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http://members.cox.net/dieselmerc/om603sig.jpg

87 300D 178k (Crazy in the head)
82 Volvo 160k 240GL Diesel

I had a leaking gasket just above my block heater n the 75. Added some Bars leaks and it took care of it until I finally put a new gasket on.

Look for all the tale tells that everyone is noting i.e pressure in hoses, oil in water, water in oil etc. The thermostat is pretty easy and a cheap fix so you could do this one yourself if you wanted. Really being tested? Go to a second shop and get another opinion without telling them about the first opinion....

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'99 S420 - Mommies
'72 280SE 4.5 - looking to breathe life into it
'84 300SD Grey - Sold
'85 300SD Silver - Sold
'78 Ski Nautique

I use the Zerex g-05 like Rotor does. It also costs a tad more than the "green" stuff, it is well-spoken for here.
David

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2000 Honda Accord V6 137k miles

1972 300SEL 4.5 98k miles

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Yup, coolant in the oil, bubbles on the dipstick. But on the plus side I ran into a guy at a new years party that has some heads he will sell me for $300. Ain't life grand.

Car still runs like a champ so I think it's worth it to fix. Just love getting that big sucker out on the highway.

Thanks for all the advise.

Koop,

Have a cooling system pressure test done. That is where they have a tool with a pressure gage that pumps pressure into the cooling system and you can see if the pressure stays steady or leaks down. If it leaks down there is a leak someplace. If it isn't on the outside of the engine like the water pump, radiator hoses heater core, ETC, then it is probably the head gasket or worse a cracked head or block.

There is something called a Frabo (spelling) test but I don't know how it works.


P E H