[Vwdiesel] RE: Engine hints --- (for Gavrik Peterson et.al)

Sat Aug 9 01:27:30 EDT 2003

Val,

>I've never done leakdown tests on diesel engines.

I have an leak-down tester that was made for aircraft engines which I
used once, years ago.  You have to make sure that the cylinder is
exactly at TDC or the engine will rotate.  The tester has a regulator
that allows you to raise the pressure gradually.  As you bring the
pressure up you hear an increasing hissing sound.  At some pressure
you can hear the ring seat and the hissing sound get way quieter.
When I performed the test, the leak rate across the 4 cylinders and
the pressure required to seat the rings at was quite uniform.  All I
learned was that things were uniform and the compression rings were
free.  If I can find out what leak rates correspond to good cylinder
condition, the tester might be useful.

>Then I'd run the car for 5 or 10 hours.

I take it you mean drive it in some manner for this amount of time.
Do you use a particular type of oil in the sump for this period?

No one on the list has expressed a preference for a particular type of
head gasket.  I still would like to know if it matters what head
gasket I use.  Do you have any preferences concerning the manufacturer
of the head gasket?  The German manufacturers that can be ordered from
the local distribution are: Victor/Reinz; L-Ring and Gertse (not sure
about the last two names).  Are there any similar issues with the
stretch bolts?

  --  Gavrik

On Sat, 9 Aug 2003 01:42:15 -0400 (EDT), you wrote:

>I've never done leakdown tests on diesel engines.  I simply go with the
>compression, on a cold, and a mildly warm (140F?) engine.  I do the
>warm first.  For a compression gauge, I use a KD tools one, with VW,
>Mercedes, and a few other quick disconnect adapters.  I think I paid $50
>or $60 25 years ago for it.  I can't say what's available right now,
>but I'd check out the options.
>
>If you're loosing coolant, and have cross contamination, there is a 99%
>chance that you need to replace the head gasket.  But your problem may not
>end there.  If, for example, you had a crack in the cylinder head, which
>put combustion byproducts into the coolant, that would indicate a new
>head.  You could also have a problem with the block.  Fortunately, block
>problems are very rare.  Cracked cyl heads, which put combustion
>byproducts into coolant are rare.  Usually, it's just a cyl head gasket.
>They're just that way.  Al and cast iron have different coefficients
>of expansion, and the problem begins there.  I know gas engines which
>get less than 100Kmiles on a gasket.  VW diesels tend to get 125 to 225Kmiles
>per gasket.  Unless there's something wrong.  I had a car, which fresh from
>the factory leaked.  It really leaked one -20F morning.  And it kept leaking
>between #3 and #4, in the front, right until I rebuilt the head.  (Guides,
>clean-up milling, and seals.  Valves faced, but OK.  Cost $135 about 19
>years ago.  That engine went to 350Kmiles.)  The new cyl head gasket, or
>the very light surfacing of the head apparently helped.
>
>On breakin...
>I'd inspect the belts, hoses, etc.  Then I'd run the car for 5 or 10 hours.
>Plan on belts, cooling pump (while the belts are off), new coolant (use
>the currently available diesel rated coolant), brake flush and bleed,
>and any other preventative stuff.  But I'd try to put some time on it
>first.  That way you'll know that it's basically working, and if there's
>something that's going to fail early, it'll have a shot during your breakin
>runs.
>
>Personally, I'd do all systemic fluids (yes, probably the power steering fluid),
>filters, head and gasket (apparently).  While there, water pump and all
>hoses and belts.  For my 92, I spent about $90 or so for all the belts
>and hoses this past winter.
>
>While you have the head off you can service your injectors.  Or simply wait
>until after the head is back on.
>
>I hope this is of some help.
>
>Val
>
>c That horrible H-man
>
>
>
>
>
>
>
>>
>> Hagar,
>>
>> Looks like you wake up early.
>>
>> Thanks for the input on the re-ringing and rod bearings question.
>>
>> The reason that I need a new head gasket is that it appears that
>> combustion products are leaking into the coolant system.  I described
>> my reasons for suspecting this in my first post to this list, which
>> had "New Diesel Guy With a Problem" on the subject line.  I reproduce
>> the relevant part below:
>>
>> >Some time ago I noticed that it was using coolant.  I expected to
>> >find a leak but found nothing.  Then I noticed that if the engine
>> >was warmed up, I could hear venting from the cap on the expansion
>> >tank.  I also noticed that when I squeezed the radiator hoses,
>> >they seemed to be under higher pressure then normal.
>>
>> >Next I checked the venting pressure of the cap.  It appeared to
>> >be within spec.  Motivated by guilt, I proceeded to change the
>> >coolant.  When doing this I like to clean the residue that coats
>> >the bottom of the expansion tank.  Normally I find residue that
>> >is brown in color.  This time the residue was black.  Changing
>> >the coolant made no difference.
>>
>> It is not accurate to describe myself as a 'new' to the diesel
>> business.  It's just that I have been a mail list lurker for two years
>> and am finally motivated to start posting.  The 'problem' part is
>> entirely accurate.
>>
>> You asked about the Rabbit.  It's a naturally aspirated 84' engine in
>> a 83' body with two notches on the head gasket.  It was wrecked while
>> parked on the street in front of my place (it became a federal case --
>> long story).  After sitting in a garage for two years, I transferred
>> the engine into a 83' Rabbit that I bought for $400.
>>
>> So the history of my Rabbit is:  Bought it at 39k miles.  It was
>> wrecked at about 80k miles.  After replacing the body I have put on
>> 90k miles for a total of 170k miles on the engine.
>>
>> You also asked about the injection pump.  I am not sure how to read
>> the numbers, so below I reproduce everything I see on the front of the
>> pump:
>>
>>     BR. 0 0460 494 130
>>       VE R 136
>>            068 130 109
>>     015 531      22845
>>
>>     * the pump has a blue dot
>>
>> The Rabbit has been loosing coolant for months now.  The rate has been
>> quite slow and I have not seen anything that would suggest that
>> coolant is getting into a cylinder or the oil.  It makes me wonder if
>> the leak only exists when the cylinder pressure is high.  If this was
>> the case significant amounts of coolant might be prevented from
>> entering the cylinder.  Is this possible?  Am I nuts?
>>
>> The problem that I have is that this is my only automobile.  At least
>> live in town and am close to parts and tools.
>>
>> This weekend I plan to check the compression and if I can get some
>> air, do a leak-down test.  I might also remove the coolant and
>> pressurizes the cooling system to see if that tells me anything.
>>
>> I will download the list archive.
>>
>>
>>   --  Gavrik
>>
>>
>> On Fri, 8 Aug 2003 13:05:46 -0700, you wrote:
>>
>> >This is a multi-part message in MIME format.
>> >--
>> >[ Picked text/plain from multipart/alternative ]
>> >Now  Gavrik Peterson  it not for me to tell you what to do , there are far=
>>  more experienced fellas here . Val Christian probably owned the first dies=
>> el VW in America.  But here is what I did.   With head of  level all piston=
>> s=2E Then pour a measured amount of thin oil (fuel will do) in the cylinder=
>> s and see how fast it disappears down to sump. The last one I did # 3 was s=
>> itting there for days. Compare cylinders and write down, so you can find it=
>>  next time you do compression check.It gives you one more clue with little =
>> effort.   By the way the machinist is right in Seattle it makes no sense to=
>>  put old rod bearings back in with that kind of mileage.    ---Re ringing t=
>> urns out great if done right. --if you have the money do it.  Out here in t=
>> he backwoods we do what we have to do to get going.   The bores seem to go =
>> a long long way on diesels due to lubing from fuel.     Gasoline is murder =
>> on some engines in that department so do not compare mileage that way, to a=
>>  gas job..     Have fun
>> >Hagar.
>> >
>> >PS: tell us why you are installing new gasket ?
>>
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>