Leather,

I test my prechambers every time I use my car. If it runs good, gets decent mileage, doesn't knock and has good power, my pre-chambers are OK. And I'm not about to take them apart. That's why I like Diesels: so I don't have to be fixing them all the time.

I know we are never going to agree on R&R the prechambers so I'm not making any more posts about it.

P E H

I never intended to change your mind. You simply gave me the chance to explain to others why it might be a good idea to choose a time to inspect and clean the precombustion chambers... thanks for arguing as long as you did....

I'm lost in the prechamber discussion.

Personally- unless I've got a symptom.. I'm not pulling the part. Heck he's looking for possible oil consumption reduction. Maybe he should dismantle the engine and compare everything to spec?

On installing valve seals. It's easy. I used a crowsfoot on a 6" 3/8 extension for seating them. A little time with a big screw driver will remove them. Just pry a little on one side and then switch.

For general removal- pull the rocker arms. Then with a cylinder on tdc(you can determine this by camshaft position instead of pulling a pre-chamber), unscrew the valve adjuster and remove spring.

Not hard, will probably remove the faint bluish smoke at idle. Don't expect a reduction in oil consumption that's noticable. Gassers have manifold vacuum which pulls the oil past the seal. Diesels it's just splash and gravity.

Check valve guide wear by feel while it's apart for the new seal.


Michael

__________________
Michael McGuire
83 300d
01 vw A4 TDI
66 Chevy Corsa
68 GMC V6 w/oD
86 300E

"I'm lost in the prechamber discussion."
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LOL

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"Personally- unless I've got a symptom.. I'm not pulling the part. Heck he's looking for possible oil consumption reduction. Maybe he should dismantle the engine and compare everything to spec?"
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Everyone has different thresholds for " symptoms" ... We don't know what yours are....
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"On installing valve seals. It's easy. I used a crowsfoot on a 6" 3/8 extension for seating them. A little time with a big screw driver will remove them. Just pry a little on one side and then switch. For general removal- pull the rocker arms. Then with a cylinder on tdc(you can determine this by camshaft position instead of pulling a pre-chamber), unscrew the valve adjuster and remove spring."
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Do you not recommend using the plastic protectors... or just forgot to mention it ?
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Have you every pulled your precombustion chambers ?
Have you read the FSM instructions on pulling them ?
It does NOT sound very hard to me.
While the screw out type puller is expensive... the slide hammer one could be made at a reasonable price....
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"Diesels it's just splash and gravity. "
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Are you sure about this ?
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"Check valve guide wear by feel while it's apart for the new seal."
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Is this the recommended way to check that ?
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Here are my further arguments...

1. SOME logical point ought to be chosen at which to check the precombustion chambers...

2. I say that when the valve stem seals need replaceing that that is as good an indicator as any to pick.

3. The shop manual also goes into detail about looking at the " oil streaks " on the walls of the bore ... how to recognize scoring as compared to the regular streaks... this could be examined with the precombustion chambers out.

4. It is not hard to imagine that due to the importance of those tiny holes that a difference of 2 to 4 miles per gallon of fuel could be caused by some of them being obstructed. That adds up over time.. and if it is bad enough that liquid fuel is getting past the rings you also have the possibility of oil dilution and increased wear due to that.

4. With Diesel fuel at $1.30 it costs 5.4 cents per mile for fuel if one is getting 24 miles per gallon.... and 4.6 cents at 28 miles per gallon.

That adds up over the long run...

Calm down guys, I didn't mean to start a fight...but hey...i like watching one just like the next guy.

Let me throw some diesel fuel on the fire. As correctly stated by one of the posters, the problem I am working on is oil consumption. I thought that doing the valve seals might....and I mean MIGHT reduce it some, and it certainly shouldn't hurt anything...unless I drop one of the valves into the engine.

After searching the web extensively, I have only found a few cases where it actually helped with oil consumption...and in all of those cases you could see blue smoke either at startup or idle. I though I had blue smoke on start up, but upon closer examination it looks more just like normal unburn fuel (black/grey) for the few couple of seconds...then it clears out.

So after all of this, I'm not sure I need to change them. Part of the problem, I'm sure, is driving full throttle in 90+ degree heat. It has cooled down some lately, so I'm going to watch the oil consumption more closely to get a better handle on the total oil usage.

In the meantime, I'm back to tuning the transmission on my 300D. It currently suffers from the dreaded harsh 1-2 shift and flaring 3-4 shift.

Joe

240JOE,

And after all that work I did tell you how to get the pistons to TDC. YOU get no more help from me. LOL

P E H

240Joe,
Your attitude about it possibly helping ... and not doing any harm as long as you don't drop a valve is correct . And I brought up the part about the bore streaking because this is an oil useage issue and that is the only way to see if something has gotten into the engine and produced visible damage to the bore walls....
Of course this also makes it fool proof in terms of not dropping any valves because you can SEE whether the piston is up or not on each set of valves you start to address with new seals...
Most of us have old cars with lots of miles on them and are not the original owners.... we paid typically one third ( or much less) of what even some cheaply made new car would cost. I say that once in a while it pays to invest in a new tool and acquire the knowledge to perform some check or service on these old cars to make them even more frugal to drive and possibly make them serve us even longer.
The opposition on this thread have only offered up things like their own ( perhaps overly frugal ) philosophies, or fear of the unknown, or lack of appreciation of the critical nature of those little holes to the efficiency of our diesels... and in doing so they contradict the Factory Shop manual..... some people don't believe in ANY preventative maintenance.... always waiting until some failure SLAPS them in the face before responding... I just say that logic would dictate that at some point these holes ought to be checked and cleaned... and it seems that the need for the replacement of the valve seals... as an indication of a certain amount of useage of the engine....would be a good standard. ( or excuse ).

To answer your questions.. leathermag,


I have zero idea of your qualifications. I am a ASE master techician, whom graduated 3 X from engineering school. My current profession is a stress analyst. But I do consulting on fatigue, LE work and a host of engineering/assembly/service problems with fixed and rotor wing aircraft.

During my tenure as a mechanic, I worked heavily on Porsche's and quite a few MB's. I've pulled more pre-chambers, wrapped more timing chains, and adjusted more valves than any DYI'r will ever do in a life-time.

Have you ever pulled a prechamber? Your the one suggesting it's need and it's ease. Mercedes suggests it for crack inspection under some circumstances. Like someone starting one with ether would lead me to pull chamberes. Strange noises.

Of the ones I've pulled, they are either perfect without clogged holes, or the end is completely gone (via injection/injector problems)

As for my suggestions on v/s. They were supplimental, obviously someone whom does not know to use the valve seal protectors by reading the shop manual (not haynes) or experience has no business doing the job. By looking at a specialty tool catalog and saying you need to buy the tool to do the job, just shows you've never done the job. I was just pointing to a work around method. I've got lots of tools, but don't have any special v/c installation tools.

I will say again, it's pretty hard to drop a valve. you just need to have the engine close to tdc for that cylinder. The diesel combustion chamber is small and the valves are perpendicular to the piston. Gasers have problems when the valve angle is slight and the chance of bending a valve is higher.. but gasers you put the piston at TDC and fill the chamber with compressed air.


Michael

__________________
Michael McGuire
83 300d
01 vw A4 TDI
66 Chevy Corsa
68 GMC V6 w/oD
86 300E

You did not address my argument.... which is based on the logical extension of the instructions and descriptions in the Factory Shop manual.... a recitation of experience would pit you against the people who built the engine and wrote the manual for taking care of it... not in contrast to my direct experience with precombustion chambers....
Yes, I suggest that once every 200,000 miles , or when valve seals appear to need replacing that the precombustion chambers be pulled to check for open holes and the condition of the pin.