Head gasket change on W124 E200 - advice please.

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RobinA3

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Mar 29, 2014
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W124 E200
Hello!

My parents have a W124 E200 which they bought brand new back in 1995 and has 120k miles on the clock - it's never missed a beat in 19yrs until this weekend.

Yesterday the car over heated in traffic and was recovered back home - I had a look and found that the header tank was full of mayo - there was over a litre of mayo which points towards a head gasket failure.

I am currently weighing up the options, I could do the job myself or obviously get a merc specialist to do the job, as the car is worth about £500 the repair will cost more than the car is worth but my parents are very attached to the car and would like to have it fixed rather than scrapped.

Would anyone know what a merc specialist is likely to charge? I shall will be ringing around on Monday to check out prices but would like an idea if anyone has one.

I am confident with the spanners (my day job is an engine development engineer at a luxury car brand in Cheshire) so tackling the job myself isn't a problem as I have done similar jobs before like changing the timing chains on our Golf R32 which was a solid 3 day job!

Does anyone have an hints or tips for doing this job diy or know of any online guides for this job?

Any help and advice would be much appreciated.
 
Also could anyone tell me whether there is any oil cooler fitted to this engine as that could be a possible route cause to the oil on the coolant which would a much easier job than a Headgasket change.
 
Can't help with your oil cooler/heat exchanger query but the fact that the car overheated dramatically suggests head gasket failure. Check the water pump hasn't failed causing the overheating initially. The impeller could have failed.

Re your experience with Bentley and doing the timing chains on a VR6 Volkswagen, I'd say you'd comfortably complete this job in 10 hours. Problem is that you're likely to need to have the head skimmed as it may well now be warped.
 
the timing chain tensioner needs particular treatment, or you will experience a broken camshaft after assembly.

Also timing chain cover oil U-seal and chain guide pin needs prior knowledge.

get the Haines Manual form Halfords either 124 OR 202 (which used same engine).

Ensure only experience Mercedes Independent (familiar with this generation car) does the job.
 
Thanks for the input guys - I will be ringing around tomorrow for some info regarding whether the car has an oil cooler which is a part of the radiator and if it is then this could be the cause (clutching at straws!).
 
If it is automatic, it'll have an oil cooler for the gearbox built into the radiator.

Check the auto box dipstick.
 
As well as the gearbox oil cooler built into side of RAD, my 6 cylinder
version of engine (1995 model) has the engine oil cooler built into
the oil filter casing at rear side of engine. They have indeed been known to fail.
 
Since it overheated there is a chance that the head could have warped so could need skimming.
 
Hello!

the repair will cost more than the car is worth but my parents are very attached to the car and would like to have it fixed rather than scrapped.
Would anyone know what a merc specialist is likely to charge?


Does anyone have an hints or tips for doing this job diy or know of any online guides for this job?

Any help and advice would be much appreciated.


I paid £600 at SPR Autos Stockport, about 5 years ago, and would recommend them.

Peachparts do a howto on a 6 cylinder with cis injection, might give you an idea what the job entails.

PeachPartsWiki: Head Gasket Replacement
 
Depending on the condition of the head its about £650-700 with me.
 
if you're in the south, take it to Portsmouth, if you're in the north, Stockport, simples
As you said they want to keep the car, i've spent about how much as my car is worth, but who's counting :D
 
Thanks for all your replies.

I am thinking that it is more likely a radiator failure of some sort rather than a CHG failure due to the amount of mayo - the box has been shifting a bit harsher recently as well which is not a good sign.
 
Managed to spend a hour or so on the engine to try to determine how much mayo is in the engine and found this:






The whole cooling system is filled with the stuff so flushing it all out will be a nightmare and the possibility of the block and head being damaged from overheating is quite likely therefore I am currently trying to source a replacement engine.

I am wondering if it is worth replacing the HG on the replacement engine before I fit it? Opinions?
 
the harsh box may be the clue it is gearbox oil into cooling system, not engine oil.

gearbox oil should be red.

the vacuum unit rubber may have split and allowing gearbox oil to be sucked up into engine.

Did you ascertain the likelihood of the gearbox oil pipe within RAD allowing mixing with coolant ?

Does mayo look a bit pink ?
 
The box oil is nice and red, also level wise it's as it should be.

If it was the box cooler then wouldn't there be some signs of mayo on the auto box dipstick? Or a higher oil level due to the coolant?
 
I have also been told by Mercedes that there are 2 types of head bolts used - the engine uses 6 of one and 4 of the other - anyone know if this is correct?
 
You need to do some further investigation. I would clamp the radiator hoses from the auto transmission then remove the rad completely as you will want to back flush it anyway and try some form of pressure test to see if the auto trans coil is still OK - You will then know where you stand vis a vis radiator leaks. If its the radiator then change it- do a comprehensive engine flush with hose first - you can make up an adapter using the thermostat housing and run water till it becomes clear- don't forget the heater assembly [ mercedes advocate using a citric acid solution- so you might think about that after the initial clean out]That may cure the problem- but obviously you will need to change the autobox filter and fluid ALSO.

If the radiator passes then you will still need to flush out the system/radiator anyway before turning your attention the cylinder head gasket. Its do-able but its tempting to skimp on the essentials-- get the head planed/trued by a machine shop-- sometimes they require some welding repair also-- use only bona fide MB oe REINZ head gaskets - and renew the head bolts---- they are known to stretch.
Because the problem has been going on sometime I would be concerned about engine damage to the bores or bearings but these are tough engines - possibly a sound engine from a breaker might be a better option. That said your primary task is determine the source of the mayo before deciding your course of action.
 
Thanks for the advice.

Having a spent some more time on it today trying to determine where the oil is coming from I was idling the car for about 10mins and the coolant started to boil over and did so again when I left the header tank cap off. This has got me thinking that it could be cylinder gases getting across the gasket into the coolant gallery which is pressuring the coolant system.

Both the top and bottom radiator hoses are hot when this happens so I am pretty sure that the thermostat is working correctly.
 

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