lilayZee

Hi,

I have a 2002 C200 Kompressor W203. It has done 196 927 kms and I've had the car for about 3-4 years. It hasn't had any trouble as such during this time besides the usual stuff, services, brakes etc.

I took the car in for a service yesterday (I go to an specialist independent mb mechanic) and he noted some stuff that was worrying to me. As written on the report,

-Coolant leak at rear of cylinder head (has formed a moist crust).
-Radiator starting to leak around bottom transmission cooler fitting.

He told me it was a sign there was a crack forming in the head gasket and said he doesn't know how long it would take for it to blow completely, said it could take 1 week or 10 years. (Note that my car has never had any over heating issues and never been driven low on coolant since I've had it for 3-4 years). This has left me iffy, isn't the head gasket either blown or not or is there truth in what he says? The thing that has me worried is that he suggested putting stop leak through the coolant to help seal up any small cracks to help it from getting any worse, me trusting him I said go for it. I'm not sure what brand he used but the only thing he told me was make sure you drive the car for 30 minutes before turning it off after he put it in.

So today I started googling about stop leak and worryingly everything I read said that it's a horrible product to use and that it's just a last ditch effort to extend engine life minimally at best. Why did I need to even put the stop leak into my car then If I have had no signs of coolant leaking on my driveway and no over heating as of yet. Was this a horrible idea to use? Should I flush out my coolant and put in some new coolant?

Any advice would be greatly appreciated as I'm stressing out a bit about it. I haven't driven it since I got home from the mechanics in case it needs a flush.

Thanks,
Antoni

Alaqil

I used similar product to fix slow fog propagation on all windows after running the A/C heater on winter as interior heat exchanger slight coolant steam leak is suspected. I used Liqui Moly coolant stop leak and pure only half of recommended amount and the issue is solved and the coolant cooler still shining like always which saved me a lot of $$.

8 months later, I noticed a very small amount of engine oil spots floating in the expansion reservoir and the mechanic advised that engine oil cooler gasket is gone. He change the oil cooler and did coolant flush. He advised that this is a common deterioration issue on M271 Engines and not related to stop leak product. Now it is about a year with no issues or leaks so far.

lilayZee

Hey,
Thanks for the reply. My C200 W203 has the M111 not the M271 engine type. Not sure your answer relates to my situation.

Alaqil

Regardless the engine type, the product did not harm my engine and fixes the leak issue. Let's see if someone have different experience.

It is worth to mention that there is a caution not to use the product on cars equipped with coolant filter which I think our cars did not have.

Good luck

Alaqil

btw... I would prefer daily running the engine to it is operating temperature during this period if you are not going to use the car.

lilayZee

Ah k. That's good to hear that someone else's engine didn't suffer when using stop leak!

I was hoping someone could give me more information in regards to my coolant leak at rear of cylinder head and if stop leak would of been a good solution in regards to this specific issue.

Good idea about running the engine for a bit. Thanks.

slammer111

Is there a coolant pipe that is going on the car instead? Not sure about the M111 but the M271 has a plastic pipe back there that is known to crack and weep/leak coolant.

Radiators in early W203s are known to leak if they're made by Valeo. The transmission fluid and coolant end up mixing, which destroys the transmission. This needs to be looked at immediately. Just replace the radiator. I assume the new Valeos have the problem fixed, but personally I would install a Behr instead for peace of mind. Crawl under the car and there's a brand sticker somewhere on the radiator.

SLcharge

The failing head gasket is the problem on the engine. Get it replaced. The stop leak may last, and may not, but if the coolant continue to leak out, both the block and the cylinder head may be damaged, due to corrosion. At that time a new head gasket may not be able to seal up the leak anymore, and a repair would be costly. The radiator, get it changed ASAP, and get the transmission oil changed as well, just in case there is already water in there. If there is signs of water in the oil, ( it will drain out first ), then flush the transmission as well.

MB engines are Extreme depending on use of the right Glykole. For corrosion prevention, only use recommended Glykole, and if you don't have acces to demi water, for the mix, buy premixed Glykole.

lilayZee

Thanks for the response. This is the issue I was trying to weigh up with the head gasket. It's very costly to fix the head gasket, rough ball park $3000+ AUD is what my mechanic told me. I'd rather put that money into another car at this stage, the car only cost me $4000 AUD 4 years a go. So now I'm stuck deciding whether I should get a new radiator and service the transmission which will cost me $1500 AUD combined and hope the head gasket doesn't go anytime soon otherwise that's more money down the drain.