I'm thinking of how I'd manage the cost of this situation. Everyone has their opinion about #14 heads. Mine - there's no reason to replace a #14 as preventive maintenance. However, if the head has to come off and you're going to spend money on a valve job, I'd spend a little more to install a later casting. It's a coin toss if all you need a new head gasket. If I have a later casting sitting on the shelf, it'll go on if the #14 head comes off for any reason. Otherwise I wouldn't do more than hand clean the #14 head when replacing the head gasket. Certainly not a valve job since I have to farm out that job. I'd rather apply the money to a later head casting. Flame away.

Replacing valve stem seals will cost you a set of seals, maybe a valve cover gasket, the cost of buying, renting or fabricating tools and about 6 hours of your time. To be clear, this is done without pulling the head. Hopefully that takes care of the smoke. At least it should take care of the dribble of oil from the exhaust manifold.

The clack could be a tired or clogged lifter. You should do a quick tension check of each lifter when you pull them out to do the valve stem seals. What you can't do is check that there is good oil pressure to each lifter. A disintegrating head gasket can send debris into the lifter galleries. Could also be a nailing injector (shouldn't nail when you loosen the fuel line). Or the belt tensioner.

Replace the timing chain when it's stretched/elongated beyond the service limit. I think it's 4 or 5-degrees. Nothing mentioned above simplifies replacing the timing chain other than pulling the valve cover so you can treat it as a separate job.

Sixto
87 300D

Hi John,

As Sixto mentioned, yes... mine leak was due to was a faulty valve stem seal on the #6 exhaust valve. It was dislodged and was floating on the valve stem. This was on a brand-new #22 head that was assembled by a machine shop, however I did not realize the difference between OE and OEM seals, and unfortunately gave them OEM/aftermarket seals... which did not work well, as you can see. The symptom (besides the leak) was blue smoke which was very obviously oil burning (not white smoke). If I let the car idle when warm for 1-2 minutes, like at a stoplight, then rev the engine, i.e. when accelerating away from the light... the engine would blow a huge cloud of blue smoke out the exhaust. If I revved it again right away, the smoke cloud would be much, much less. The idling let the oil build up somewhere which was then burned out when the engine was revved. New OE/dealer valve stem seals cured my problem. More photos below.

Honestly, I wouldn't put the money into a valve job on a #14 head. I'd rather spend the money to buy a good used #17 head and bolt that on with new seals. Or, a new #22 head if you can afford it. On a budget, I'd first do a compression test to make sure the cylinders are tight (and the valve seats aren't leaking), then replace the valve stem seals with the head still on the engine, and hope that cures it. If you pull the #14 head off the engine, I would bolt it back on (with new seals) if there are zero cracks... however I would never put the $$$ into new guides, valves, etc on a #14. Just my $0.02.

Factory spec on compression for a hot engine is 26-32 bar (375-465 psi). Max deviance from highest to lowest is 3 bar (45 psi). You need to compensate for elevation (as shown here), at 3.4% per 1000 foot of altitude. Those numbers sound low, unless it was a cold engine, and/or it was well above sea level. The limit on chain stretch is 4 degrees.

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I'm jealous of your valve spring compressor Dave, mine goes to the shop Wednesday for new seals.

It looks like the exhaust/intake seals are obvious as the holes are different sizes (as well as the color)? Exhaust must be the larger hole / green?

__________________

Gone to the dark side

- Jeff

Thanks, guys, for the range of options and advice. This morning I went out to confirm this was a #14, but to my surprise it reads _ERCEDES-BENZ and underneath the number reads _03 016 20 01. about 2 inches further aft is a "2". (The flat stamping area is recessed where the "M" and the first "6" are missing.) Does that mean this is a #20? And if so is that good, better, worthy of a valve job...?

I also just found a potential parts car (87 300D w/ 137k) that the owner says has a head #603 016 01 21. Is that a #21?

I'll look locally for the valve spring compressor tool. Sixto posted that such a tool wasn't for rent via the forum. Dave, where can I get a spiffy spring compressor tool like yours? (cost?) It looks custom made for 603 head.

You win! Your numbers indicate a #20 casting. The missing M and 6 (and part of the 0 usually) confirms that it is not a #14 head also as these are machined away for the oblique injection angle of the later head's injector nozzles, you also won't be able to remove the head bolts beneath the injectors with the injectors installed in this head (a good thing).

The potential parts car head number is not valid, have him read it again.

I'm having a head (#22) cleaned, vacuum-tested, flatness tested, and new valve stem seals installed for $55, hard to complain (I'm supplying the valve seals). IMO not worth investing in a valve-spring compressor.

The later head means other things also: If you ever look for spare injector holders (the part you see), or pre-chambers (both rare to need them), as well as glow-plugs you will want to order them for a later car such as a '91 350SDL. Also, those glow-plugs are "afterglow rated" so you can search for and install that upgrade if you wish.

__________________

Gone to the dark side

- Jeff

So, maybe this motor does not have 289k, or maybe it was one that had an issue with the trap/ox. I'm sure you guys know this feels like a little ray of sunshine through the thick smoke. But the way ahead is still pretty dark. Please chime in to help me see the path:

Pull the valve cover and remove the cam towers (find and follow the step-by-step process or else...)

Have the head cleaned, vacuum-tested, flatness tested, and all new valve stem seals installed. I supply MB OE valve seals.

Reinstalling head, cam towers - do I bring it somewhere for a valve adjustment?

I still have the elusive clack/knock which could be related to the valve seal, or not. Should I invest in further diagnosis at this point?

Is this time for a new water pump, and timing chain measurement, and ...?

Check the lash adjusters/lifters while they're out. A soft one could be the noise. Number them so you each one goes back in its bore. No valve adjustment to worry about.

Have the oil passages that feed the adjusters thoroughly cleaned.

Measure the chain before you pull the head. Set cam to TDC, read degrees BTDC on the crank pulley. Lather, rinse, repeat. Average a half dozen readings since alignment of the cam marks is subject to subjectivity MB could have put the marks closer together.

Sixto
87 300D

First, I agree with babymog... for a one-time job, it's not worth investing in the valve spring tools, unless you enjoy DIY work, and re-sell the tool afterwards to recoup some of your $$$. That said:

I used to have the old-style valve spring compressor, which has a bridge (long round bar) that goes across the cylinder head, as shown in the photo above. You have to be careful not to scratch the lifter bore using this type of tool. The three requried pieces (bridge, T-handle, and "foot") are somewhere around $200 or so, maybe a bit more now - I haven't checked in a while. I sold this setup a few years ago. The OE/dealer valve spring tool kit is much nicer, and is shown here. That will set you back around $600 though. But at least it works on many different engines.

Guys, yesterday my indy diagnosed it "100% certain that it has a broken piston."

I had AAA flat bed the car to my indy for his read. I was looking for a more specific diagnosis of the changing knock-clack in the engine. Sometimes it was louder than others, and it was timed to the engines 6 firings. And the screwdriver-to-the-ear stethascope said something was amiss in the #2 cylinder. furthermore, my white-burned-smelling-smoke did not match gsxr's

gsxr wrote that his seal problem's symptom was: "(besides the leak) was blue smoke which was very obviously oil burning (not white smoke). If I let the car idle when warm for 1-2 minutes, like at a stoplight, then rev the engine, i.e. when accelerating away from the light... the engine would blow a huge cloud of blue smoke out the exhaust. If I revved it again right away, the smoke cloud would be much, much less. The idling let the oil build up somewhere which was then burned out when the engine was revved."

Mine will belch smoke steadily.

So I'm in back in the market for an engine or parts car.

Re: Parts car: I found a sweet looking black '87 sedan with a bad tranny. Any idea of demand for parts via this site?

Further diagnosis is required before concluding it's a broken piston. At least pull the prechamber and injector. I'd also run the car and loosen the #2 fuel line and see if the noise is reduced or eliminated. You really need to pull the head to tell for sure. A "broken piston" is very, very rare on these engines. A friend of mine owned a '87 300D, and he worked at a dealership. They also diagnosed his engine as having a bad piston. He swapped engines. A couple years later he was taking parts off that supposedly "bad" engine, and discovered the pistons (and entire bottom end) were all fine... it was a fragged turbo causing the problem! Lesson learned: Until you have pieces of broken piston in your hand, or photos of a melted piston, I'm not convinced.



Figures... I have a good used tranny, and I'd like to find a cheap '87 with a bad tranny. Naturally, you are 1200 miles away from me... D'oh!!! But yes, there would be demand for parts via this site, if you decide to part one out. If the car is nice enough, though, I'd fix it. These are rare enough (only ~2500 sedans imported to the USA) that it's a shame to kill one off.

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But Dave, if it is a southern California car it could be worth it. What's 1200 miles......

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Be careful of the toes you step on today, as they may be connected to the ass you have to kiss tomorrow. anonymous

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OK, so I go to the shop to move the car to a nearby shop that will charge for a compression test, and figure I can limp it over there. But no...now the engine doesn't run. It stops right after it starts. I'm not having any luck finding a loaner compression tester. Is there one on the forum?

Maybe this weekend I'll get a look at the for sale 87 300D sedan with the bum tranny.

What FSM (factory service manual) do you guys recommend for engine work?

www.********arizona has:
Robert Bentley
Repair Manual - Book Version; 1986-1995 Mercedes 124 Chassis Owners Bible; OE Factory Authorized Bentley Number GMOB. 1 per car. $59.90 Sale: $32.66

www.mercedesmanuals.com has: 2 CD set
Mercedes-Benz 260E, 300E, E320, 300E, 400E, E420, 500E, E500, 300D, E300D, 300CE, 300TE, 300TD 1986-1995 Repair Manual
Our Price: $54.00
Sale Price: $47.00
Availability: Usually Ships in 24 Hours
Product Code: W124

Can I just remove the valve cover, etc. and then remove the entire head without removing the cam towers? Is there a process for this on the forum? How much has to come off, what has to come off the front? (radiator? water pump, ...)

There are head bolts under the cam towers so the cam towers have to come off. Nothing has to come off the front of the engine. Well, the radiator hose and maybe the fan to gain access to the guide rail pins.

Get the MB manuals.

Sixto
87 300D

Yes you can remove the head with the cam in place, you will need the longer triple-square bit though as it has to go down through the clearance holes in the towers to loosen the head bolts beneath.

__________________

Gone to the dark side

- Jeff

Jeff, as cool as it sound "you can remove the head with the cam in place, you will need the longer triple-square bit though as it has to go down through the clearance holes in the towers to loosen the head bolts beneath"

Where does one get "the longer triple-square bit "