This morning, I pulled to a stop after driving
30 miles on the highway. There was a fast
ticking noise. I thought the timing chain was
making the noise like the tensioner was
not working. I have never heard this ticking
noise before today.

It immediately started running rough, and acting
like it was going to stall. I made it another
mile to my house and shut it off.

Then I changed the fuel filters hoping it was
an easy fix. The filters did not do anything.
There are no leaky fuel lines at the injectors.

It is smoking a lot now too since this started.
It's black smoke. When the engine is revved up,
the "miss" is not noticeable. The roughness is
most obvious when idling.

There was 1/4 tank of fuel when this started.
I just filled it up and it is the same.

Top speed is just 70mph. It used to be 80 mph
before this started today.

I am guessing that it has a bad injector.

Would a valve come out of adjustment that fast?

- Jeff

__________________
- Jeff

1957 W121 190 (history)
1966 W108 250S
1967 W108 250S (parts)
1982 W123 240D (history)
1989 W124 260E

I would suggest that you start with a compression test. The fact that the rough running was immediately associated with noise is not a good thing.

Start with a compression test and it may take some exploratory surgery after that.

Best of luck,

Are you suggesting a head gasket? Should I
expect to see oil in the coolant? Will check
it as soon as it gets light out.

Would a fuel starvation problem cause the
valves to tick? I assume it's the valves
that are making the noise. What I'm thinking
about (hoping for?) is a bad injector or a
plugged fuel strainer in the tank.

- Jeff

I/m not really suggesting anything, and I didn't mean to scare you. It's possible that the noise and the smoke are coincidental. It's difficult to know without listening myself.

But, if you do a compression test, then you will either be relieved because the compression is okay, or you'll know you're gonna have to dig deeper to find the problem.

Best of luck,

My mechanic said that there was low compression
on #1 cylinder. 200psi. The others were around
360 psi. Is "psi" the correct term for
compression?

They also said that the valves on #1 and #3
were bad.

They were checking the rings but think they
are okay.

They said the timing chain appears to be
original. Not sure how they could tell.
Maybe they lined everything up and found
it to be more than 5 degrees off? Anyway
they will replace that too.

How many hours should this job take?

complete valve job including seals, head
gasket, timing chain.

should they necessarily replace the tensioner?

thank you,

Jeff

Actually 200 being your lowest cylinder is not terribly bad. My big concern all along has been the noise. What did they say about the noise?

Good luck,

They said the ticking noise was the valves.

I'm concerned about your mechanic's report of the valves being "bad." Have you had the valve clearance adjusted recently? This is part of routine maintenance for this car and should be done every 10k-15k miles. If the valves are out of spec, they will either close too soon and stay closed too long, or they won't close enough. I presume this could give the same symptoms as a burnt or otherwise damaged valve. Bad valve adjustment could theoretically make noise as the camshaft lobes slap against the valve rocker arms. Even properly adjusted valves make SOME noise.

Low compression could also be a sign of poorly adjusted valves. Of course, it could also mean some engine damage. My '83 240D had 200psi on #1 cylinder and it turned out the piston ring lands were cracked off and I needed a new piston. I think Larry Bible had a similar problem on cylinder #1. That was a 5-cylinder, though, correct?

Timing chain should be replaced after 100k-200k miles, depending on quality and frequency of maintenance, especially oil changes. More maintenance means your chain lasts longer. Of course, if it's stretched then by all means replace it. Also replace the plastic & rubber slide rails.

Chain tensioner, hmm, that's hard to say. It's easy enough to replace later, BUT it's even easier to replace now. I replaced my tensioner when I replaced the timing chain about 2 years ago.

Now, the $64,000 question: How familiar is your mechanic with Mercedes in general, diesel engines in general, and this engine in particular? I wouldn't trust just any shop with this engine, even if it is a reputable and honest shop that's worked on your Toyotas and Chevys for the past 15 years.

My theory is usually to try the cheap stuff first: adjust valves, clean injectors and rebuild if necessary, adjust injection timing. If none of this helps, THEN dig a little deeper.

Good luck and keep us posted.

- Nathan
'83 240D "Steiner"
'00 New Beetle TDI

I don't know what he means by "bad". Trouble
is, or maybe not the trouble, depending on
how you look at it, is that he knows these
cars and he always fixes my problems when I
bring the cars to him. The trouble is also a
language barrier. He's a bit temperamental and
can be difficult to understand. Anyway, I
end up not asking as many questions as maybe I
should because he fixes the car. These two
guys have worked on the old Mercedes cars for
a long time. When I bought my '57 190 in
1989, they were the guys I brought it to.

They may only be doing valve guides and seals.
Perhaps that's what they meant by bad. They
are reasonable. I'll keep you posted. He said
he would check the tensioner and advise if it
is worn. The valves were supposedly adjusted
last December or 1,500 miles ago. That's 1,500
miles, yes. I was just getting ready to do the
job myself (friend loaned me the wrenches, had
the valve cover gasket, etc.) when this happened.
He said if the rings were bad they would do those
too but I guess they held oil. Injectors were
also on my short list. They will be replaced
too. I'll try to get the old ones and perhaps
use them as wampum. They can be rebuilt right?
Will keep you posted. Thanks for the comments.

These guys will wonder why I have so many
intelligent questions tomorrow.
Jeff

I visited the garage this morning. The #1
cylinder ports were wet with oil. The other
cylinder's ports were dry. He said that the
valves needed to be ground. I'm still not clear
on whether they are replacing the valves or
grinding them. Total for job would be around
$1,400. Including:

(*) valves (ground or new?) & seals
(*) timing chain (guides too if needed)
(*) injectors & seals

They were also going to pull #1 piston to
check the rings. They fill the cylinder w/
oil and let it sit. It drained, but not quickly.

Does this price sound to be about right?

Should have it back Monday.

Now I'm forced to drive my '66 250S everywhere.



- Jeff

When I said they filled the cylinder with oil on
top of the piston and it drained, I think it
sat all night and there was still some in there
this morning, but some in fact had drained.
This sounds like the rings are okay to me.
Not sure how one normally tells how they are bad.

Jeff

Jeff:

Ticking is from a loose valve -- tight ones don't make noise because the follower is always tight on the cam lobe and the valve doesn't seat. This will burn the valve and seat, and require grinding.

Putting oil on a piston to see if it drains down overnight isn't a proper way to check rings, although it more or less works. If there are still honing crosshatch marks on the cylinder wall, the rings are fine. If there are scratches or shiny, no honinig mark areas, the rings (and cylinder) are bad. Pulling the piston will require new rings in any case, as the old ones won't work well once removed.

Oil in the ports in the head indicates worn valve guidesand excessive oil leakage into the head. A valve job will fix this -- the guides are only about $4.00 each and easy to replace.

Is you mechanic from Eastern Europe by chance?\

The price for the work sounds reasonable.

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

Yes, the guys are eastern European (Poland).

I'm still not sure how a valve can come loose
and/or out of adjustment that quickly.
Is that how they die?

Jeff

It could be that the valves were not adjusted properly last time - e.g. using the cold clearance values on a hot engine or vice versa.

Also, the valve clearances are held with a double-nut setup. The top nut (a cap nut) is adjusted to spec, and the bottom nut is tightened against it to lock it into place. If the nuts weren't tight enough against each other, they could un-adjust relatively quickly (i.e. over 1500 miles).

I just hate to see diesel owners (and their cars) get burned by mechanics who don't know about these engines. I speak from (almost) experience, having dealt with a guy who told me I needed a new timing chain when all I needed were clean injectors, and also told me I needed a new rear differential when all I needed was rear swar bar linkages. It sounds like your mechanic has been around these engines before, in which case it's just fine to trust his judgment on a bad or burnt valve.

Also, injectors can be rebuilt if you find a shop willing to do it. I had all four of mine done for around $100 by a local shop about two years ago.

- Nathan
'83 240D "Steiner"
'00 New Beetle TDI

Jeff:

Thought so -- your mechanics are used to actually repairing parts rather than just replacing them with new ones! Had to, since where they learned to "mechanic" new parts weren't available.

Sounds like a fried exhaust valve to me, along with worn out guides. This would give the low compression and smoke, along with noise from a loose intake valve. 1500 miles would be plenty to cook the exhaust valve if someone adjusted them "backwards" -- intake clearance on the exhaust and vice versa.

Good luck!

eter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!