Car: 1992 190E 2.3 8V

The car had a bad head gasket (oil in coolant, major oil external oil leaks) so I replaced it. The head was decked 0.005" and it had to be welded in cylinder 4 because it was damaged (didn't notice the damage when I pulled it because of carbon buildup, the shop told me after they cleaned it). I re-installed the head, followed the instructions for torquing (the instructions for the gasket had a different sequence than the manual, I follower the gasket instructions) and I reset the tensioner (pulled the plunger, re-inserted it from behind until first click, then put the spring and cap back on.

I started the car yesterday, everything seemed fine. I went for a short drive, no leaks, everything good. I went for another longer drive this morning, got the engine to 90C, highway driving and all. Just when I was about to come home, the engine started ticking loudly. Kinda like a valve lifter tick, but it could have been an exhaust leak right at the ports too.

-Checked all the manifold studs, all good
-Found a vacuum leak, fixed it
-Spark plugs all tight
-Opened the valve cover, no visual defects
-Good oil pressure/oil level
-If I push down on the lifters, they are all tight (would a stuck lifter be loose?)
-Timing was good when I put the head back on. I figured since it ran fine this morning it was ok. Could it have skipped a tooth even after driving for a while with the tensioner good?

I need the car by tomorrow, its 4:15 PM and I'm panicked.

Remove cam cover, rotate engine by hand, checking each valve clearance with a .003-.005 feeler. If you find one that is not zero, that may be the source of the noise.

Ok. Feeler gauge between what and what? And I guess I check the clearance when the cam lobes are facing down for that valve?

Thank you for your help!

Feeler between the heel of the cam and the follower.

I've had lifters take a long time to pump back up or get some dirt in the check valve. It is difficult to say what is going on as I'm not in front of the motor. If you think you have an exhaust leak, does it track throttle opening / Neutral - Drive and not necessarily engine speed?

An exhaust leak will be louder with load due to more fuel being burned in the cylinders / more air flow where a mechanical issue will track RPM only.

What check valve? The lifters taking time to be pumped back up makes some sense, however how can it be explained that the engine was running perfectly then all of a sudden this happend? Weren't the lifters pumped back?

It seems to be RPM-related.

I took a video of it idling (tilt your head haha):
https://youtu.be/4Er0lWZabO8

I also revved it up after that, but it seems like it's running on 3 cylinders too (listen at the choppy idle in the video)

I'm on a dial up connection so UT won't load for me.

I'd take a look to make sure all the lifters are in place and one isn't flipped over. I don't know how your specific engine is built up but if the lifters are in the rocker arms, it is possible to flip one over and it won't receive oil.

The check valves are inside each lifter and not visible without taking it apart.

If you have such a rough idle, pull the wire off the injectors one at a time and see if there is the same effect on each cylinder. If you pull a wire off and there is no or little change, that is the cylinder with the problem.

Sometimes with a rebuild and / or frequent engine starts stops, the lifter never gets all the air out. If that lifter is under compression ( engine stops with a valve open ) the lifter bleeds down and takes a while to refill but this won't cause much of a rough idle.

The lifters are in the rocker arms. The rockers are held onto the cam bearing cap. There are 4 of them. I took the bearing caps out, without touching the lifters. It's impossible that I mixed one up. Even if I did, the engine ran perfectly for a short period of time after the replacement! Can't do the injector trick either as it's mechanical injection and the injectors are activated by pressure only!

Could some piece of debris from removing the head and such have fallen inside the engine and damage the bearings or something?

Be very careful when removing and replacing the camshaft saddles on a M102. The FSM is full of warnings about the camshaft binding.

Check the FSM on startek for the torque limits - there are two values one for with the camshaft fitted (normal) and one for checking things with the rocker arms removed (not normal!)

I could quote the numbers for you but I'm going to be irritating to try and encourage you to look at the manual yourself!

The saddles are not all made equally! Make sure that the correct ones are in the correct position. The oil pathways need to be joined up to the right place.

The method of checking the hydraulic lifters is to push down on them with something such as a hammer...



...and compare that feeling with each of the other lifters. Not very scientific but it should help you find a weak hydraulic element if that is the case.

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I recommend you consider the tensioner - find out if it was set correctly after the head was changed. It needs to be completely dismantled and then reassembled in the correct order before it gets reused.

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Another test that might help is to remove the spark plugs - put the transmission / gearbox in neutral - hot wire the starter so that the crank turns over (but with ignition off so the fuel system isn't working) with the valve cover off. You can then see the valve train working.

Oil should be visible on the tops of each of the hydraulic elements after a few revolutions.

Oil should be seen coming out of the spray bar onto the camshaft

The tension on the timing chain should be firm after this process as oil pressure is also used in this system.


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Don't start thinking the chain has jumped a link - highly unlikely - almost impossible. If you are at all worried about camshaft position (after the head replacement) do a quick check by positioning the crankshaft at TDC and see if you can see the assembly mark on the camshaft lining up with the edge of the head casting. (You might have to turn the crank an additional 360 degrees => 4 stroke engine!)

Officially the "2mm lift test" is necessary to measure timing chain position / elongation but you'd need to swap your hydraulic lifters for solid ones in order to do this test - which in practical terms for most DIY mechanics with a M102 engine makes it impractical.


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ALWAYS turn the crank in a clockwise direction when you are standing in front of the engine looking at it! Never turn it the other way - the timing chain might snag and then you'll be doomed for ever...

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1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

When doing the lifter push test, be sure to rotate the engine so both valves are closed on the cylinder you are checking. If a valve is open you will incorrect results.

Good point - I didn't specify that the valves must be closed - 1000 apologies...

...yet another reason to read the FSM (sorry to be a bore but)...

__________________
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

How are you on dial up connection?? Does that still exist?

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1990 190E 3.0L

Dial ups still exist and will for a while. Credit card machines / ATM machines / emission test machines use phone lines to communicate.

I'm in a rural area where copper phone lines from the 1950's end up in an old house that contains the switching network. DSL isn't an option and no fiber here. Cable internet is a possibility but I don't have a TV ( don't miss it ) making an internet only connection a bit $.

I have as needed offsite access to a fast connection if I want to download a large catalog PDF. For 1 or 2 meg files I just let it download while I'm away from the computer. A dedicated fast connection would be nice but I haven't hit critical mass yet.

FOUND THE PROBLEM

...well, I think I did.

I removed the valve cover and found out that #1 exhaust rocker had about 1/8" of play in it. New lifter ordered (44$ cad, you guys in the US don't know how lucky you are with your 10$ lifters). I'll be cruising in the Merc in 2 days max.

Thanks for your help everyone.