W124 260E Engine Problem HELP!

[dc2100k]

Hi All,

My beloved 260E died last night and I'm trying to get the the bottom of what's wrong before I get my garage to pull the head. The car is a 1990 model with the M103 12V engine, 64000 miles only and all original. Car was running very nicely until last night, we just did 1000 mile round trip to London with no mishaps. Oil pressure at 2 (idle), 3 (under load). No bad noises, lots of power and very smooth. Would sit at 85 all day no problem. Recent timing cover gasket (to solve minor oil leak) and water pump (£££).

Symptoms: car started and drove 1 mile. Turned off and 1 hour later it would not start. Turns freely but will not fire at all. Fuel is getting to the cylinders. The garage have pulled the plugs and there is a spark (slightly weak). The spark at the distributor is stronger but cap and ignition leads are all original so probably could do with being replaced. The garage suggested this as a remedy until they did a compression test and the readings are 150-50-70-120-90-120 (ie. way too low and wildly differing) so they say no point until the compression issue is sorted. He also expressed surprise that it doesn't even attempt to start when they spray fuel in the intake.

I have asked them to do a leak down test and remove the rocker cover for a visual inspection as that may give a better idea.

My thoughts are:

1. Bad valve or valves
2. Bad head gasket (although no water in oil or oil in water, also unlikely to just stop without any symptoms)
3. Bad timing chain/camshafts.

Does anyone have any ideas or experiences with a problem like this? Garage estimates £1500+ to pull the head, fix any problems, do the stem seals, new head gasket, new distrubutor cap and leads. Clearly I want to eliminate any other things before I do a top end rebuild, and at this sort of money I'd be thinking about selling the car as a non-runner.

Hopefully someone can help?
James.

 

[roastbeef]

i would probably throw new ignition components dizzy cap/plugs /leads/plugs/rotor arm just in case it has lost a spark and engine has flooded with petrol and washed the bores out with the plugs out kill the power feed to fuel pump by fuse and crank it over do the same once the new ignition parts are fitted to dry the cylinders out good luck

 

[grober]

Sudden engine failure like this is unusual without some pre-symptoms. Because of the drastic loss of compression [ if real?] I would be checking the valve/camshaft timing isn't out.
http://www.w124performance.com/service/w124CD1/Program/Engine/103/05-2152.pdf

 

[dc2100k]

Thanks for the insight. The car was running really well prior to this which is why I think it is not catastrophic engine failure.

I suspect the ignition components are weak and need renewed (as did my garage) but flooding (from cranking the engine) wouldn't cause the *varying* compression between cylinders, would it?

I think the timing requires a closer look - is it possible that the timing chain could jump under normal use?

Cheers, James.

 

[brucemillar]

Timing chain would have to be suspect, either for jumping and stretching or a tensioner failure.

On my M103 the engine failed without warning. It just stalled as we pulled into a Motorway Services Car Park. When attempting to re-start it was dragging the engine, like a low battery. It did restart but sounded horrible. Compression was excellent on mine. It was a bent Crankshaft caused by oil starvation. We found heavy sludge in the sump with no other evidence of any failure. The big ends were about to go and possibly would have done so, had the crank not got there first.

I would get another compression done with another gauge or try this gauge on another known good engine. If the gauge is good and the test is still bad? Drop the sump and have a feel around for any bits of ring/metal.

 

[219]

Having had several M103/104 engined cars , I can echo the suggestions that ignition components make a huge difference - on more than one of them , just changing spark plugs cured a problem where they would start from cold , run a short distance , then die , and not restart until cold again .

I'd certainly suspect the distributor cap/rotor arm , and also perhaps try an ignition coil from another car ( a dead coil was the reason my 300SL-24 died at the roadside a couple of days after buying it - turned out to be an aftermarket coil and borrowing the coil from my 190E got the car running again until I sourced the correct and genuine coil for the car ) .

These things are some of the less expensive things to try , and I often believe that if diagnosis proves difficult , to always try the simplest and cheapest things first .

If you are committed to keeping the car and fixing it , then you would most likely be replacing these things anyway .

 

[dc2100k]

Thanks again. I am going to ask them to do the leak down test and inspect the timing first - as long as it does not indicate a defective head I will get them to renew the ignition components (plugs NGK BP6EF, ignition leads, distributor cap, rotor arm & possibly coil). If this does not fix it then I will get them to take the head off for more scrutiny.

Thanks everyone for your advice. What is the best way to clear the flooded engine if that is the problem giving the low compression readings? Pull the fuel relay and crank with a little oil in each cylinder?

 

[roastbeef]

not sure how the relays are wired up but basically you need to disable the fuel delivery but keep the ignition spark to burn of the excess fuel if this is the problem once it is turning over the pistons will get oil where they need them
I only suggest it could be a over fuelling issue as you say you only drove the car for about a mile from cold switched off left for a while then tried to restart where I reckon the cold start device has delivered another dose of extra fuel into a cold engine already enriched you can unplug and start these age injections with the cold start disconnected with no draw backs

 

[GP801]

We had something similar with an old 300e-24. Tiny crack in the distributor cap was the culprit. I would certainly look at these items first.

 

[brucemillar]

If I may just say again.....

Compression needs looking at again BEFORE spending out money. It may well be that the bores are flooded, giving dodgy readings (I am not sure on that) but you do need to understand why the readings are out by so much. If that is the issue? Then you can start to think about moving forward.

 

[dc2100k]

Hi Bruce, the leak down test and check of the timing chain should give an idea of whether the low compression readings are head or head gasket related no?

If it is the bottom end then we have big problems but at 64k miles with many oil changes and no obvious signs of distress prior to stopping this is surely unlikely? Engine turns freely with no bad sounds, just will not fire.

 

[brucemillar]

Agreed. My point was more generic. In that I believe that you need to understand the compression issues (if they are real) before proceeding into ignition etc.

There are many really great people on here who will jump in and help ( I see Grober already has). Keep posting your progress.

 

[optimusprime]

Would go along with another compression test . You do have three low cylinders .Another check would see if they are the same figs . Good luck hope this is an easy fix ..

 

[grober]

Agreed -- the only thing steering the OP away from a simple ignition related fault are those anomalous compression readings.

 

[neilrr]

Is the garage advising you / working on your car a MB specialist, 'German car centre' or general all makes place?

 

[219]

Thanks again. I am going to ask them to do the leak down test and inspect the timing first - as long as it does not indicate a defective head I will get them to renew the ignition components (plugs NGK BP6EF, ignition leads, distributor cap, rotor arm & possibly coil). If this does not fix it then I will get them to take the head off for more scrutiny.

Thanks everyone for your advice. What is the best way to clear the flooded engine if that is the problem giving the low compression readings? Pull the fuel relay and crank with a little oil in each cylinder?

Just remove the spark plugs and leave half an hour - any fuel in the cylinders will evaporate .

 

[rorf]

I have seen many low mileage old cars with low compression readings due to glazed cylinders caused by short gentle driving trips in town with very extended oil changes.

Bent crankshaft on a 6 cylinder Mercedes engine with sludge in sump - unbelievable

Possibly get your car to a garage that knows the older Benz to get a truer evaluation.

At 64 000 miles those old Benz engines haven't even run in, unless oil and coolant service intervals have been abused.

 

[v24pug]

You could check the Ht system from the coil could be low voltage coming from the coil giving low spark thus flooding boars. What is the temp if it is overheating could point to head gasket and low comp leaking over head

 

[dc2100k]

Great news. The garage has replaced the plugs,leads, distributor cap and rotor arm and she has fired right up. Thanks for all the great advice, I'm not sure exactly where the low compression readings came from other than maybe bore washout from turning over so much without a spark. Given that she is running nicely again I'm not going to strip the top end down for the time being. I pick her up tomorrow and I'll do a 50 mile run to check her performance under all conditions. Thanks again, James.

 

[optimusprime]

news

Good news James ..enjoy