piston rings

[nessie]

hello we are in santiago and are having our crankshaft seals front and back changed. we need to change the clutch plate as well as the piston rings.
how many kilometers is normal for the wear of these items. we have only 65000 kms
and has anyone heard of putting a reverse thread on the crankshaft at the back to return the oil to the sump, they say this was done with all the military and bus om352 engines over here.
has anyone got the part numbers for the oil rings for the axles at the propeller shaft. and are they the same for front axle and transfer box.

many thanks
david



http://www.nessiesadventures.com

[landwerk]

Hi David,

I do not think that there is any wear of Piston Rings at 65.000 Km.
If the crankshaft oli seals were bad , the clutch plates may get oiled.
This seems possible .

A svereal OM 352 had to be rebuilt here in this Forum. But i cant remember anyone rebuilt it for the reason of piston ring wear.
Some camshfts were broken etc.

Try to check you engine carefully before doing a lots of work maby for less.

At a mileage of 65.000 Km even a OM 352 shuold work without any problems.


Oli

[Uwe]

Hi,

when talking about what is 'normal' we have to consider that the history of the cars is often not known. In a regular machine life, 65'000 km shold be nothing for a OM352. But maybe the air filter was unmaintained some years, the motor oil wasn't changed or had bad quality. Who knows? Talking generally is hard in these cases...

Uwe

[nessie]

hello thanks for the fast reply.
when we take the oil filler cap off there is a blow back coming out, we presume this is compression from worn piston rings.
we have taken the engine out and the clutch plate is very worn, and the crankshaft bearings are also worn, we think this was from lack of oil changes as well,
many thanks again
david

[Pirx]

hello we are in santiago and are having our crankshaft seals front and back changed. we need to change the clutch plate as well as the piston rings.
how many kilometers is normal for the wear of these items. we have only 65000 kms
and has anyone heard of putting a reverse thread on the crankshaft at the back to return the oil to the sump, they say this was done with all the military and bus om352 engines over here.
has anyone got the part numbers for the oil rings for the axles at the propeller shaft. and are they the same for front axle and transfer box.

many thanks
david



http://www.nessiesadventures.com

Hello David,

for the normal or abnormal wear of the piston rings, everything has been written above.

As far as I know, the reverse thread on the crankshaft is already there on the OM352 engine? If not, you might have a very old engine that is not yet fitted with that feature. Anyway, this is a well known technique and nothing special, but don't expect a wonder in case of reduced oil leaking. Even with that thread, there is always some oil leaking through the seal. It is the principle of that kind of seal, to be wet by oil and thus let some small amount of oil pass through. The wetter the seal is, the better it holds back the big amounts of oil ...

For the oil rings of the axles and transfer box, it is impossible to find out the correct part numbers if we don't even know the type, VIN and year of construction of your truck. ***sigh***

Pirx

[vikingswen]

Hello David,
You should definitly do a leakdown test. After pressurizing the combustion chamber with the piston at TDC and valves closed. If you have blow by into the crank case your compression rings are not sealing. If you hear air escaping in to the intake or exhaust it will be a valve problem.

Good luck Swen

[nessie]

hi sorry to take so long to reply but was away from our truck.
VIN 353102.4249205
year 1977
type LA 911 B

many thanks
david

[Pirx]

hi sorry to take so long to reply but was away from our truck.
VIN 353102.4249205
year 1977
type LA 911 B

many thanks
david

Thank you David,

but it will last until monday afternoon (at least) until I'll be able to search for the part numbers ...

Pirx

[Pirx]

VIN 353102.4249205

Are you sure you didn't forget one number? The VIN should consist of 14 numbers, yours is only 13 ...

Pirx

[nessie]

yes you are right the number is VIN 3531021.4249205

cheers
david

[Pirx]

has anyone got the part numbers for the oil rings for the axles at the propeller shaft. and are they the same for front axle and transfer box.

Hello David,

I still encountered some problems when trying to identify the parts in your truck, but I think, these numbers are the correct ones:

Front Axle:
A 011 997 74 47 seal
(A 009 997 63 47 or A 012 997 29 47 may also be used. These are the same seals, but made by another supplier.)

Rear Axle:
A 016 997 68 47 seal
(I assume that you have a HL4-axle, not a HL3 or HL5. Both are very rare on a 911.)

Transfer Case:
A 003 997 75 46 seal
This item is needed 3 times for the transfer case. It is the same for the propeller shafts going to the engine, the front axle and the rear axle. It is only valid, if your truck is equipped with the VG 325-3W transfer case. If you use a lever to shift from 2WD to 4WD, it is this kind of transfer box.

If your transfer box is operated by turning a pneumatic switch, it is a VG 500-3W. In this case, you will need this part:
A 016 997 49 47 seal (3 times, the same for engine, front and rear axle)
(A 012 997 57 47 or A 012 997 64 47 may also be used. These are the same seals, but made by another supplier)

Good luck,

Pirx

[nessie]

many thanks pirx.
we have the lever transfer box so this will help a great deal.

the gearbox should have ATF or gear oil in it. the mechanic says gear oil so we are not so sure have tried to upload a picture of the new groove for the crankshaft seal

cheers david

[/img]

[Pirx]

the gearbox should have ATF or gear oil in it. the mechanic says gear oil so we are not so sure

Hi David!

Is what I quoted above a question? I think so ...

In case of the gearbox, there are many possibilities, which type of gearbox you have. Depending on that, the oil to use varies ...

Most likely you will have a Mercedes-Benz G32 gearbox (new designation of that is G3/36-5/8,98). For the year of construction of your truck, this will need to be filled with ATF Type A Suffix A. Don't use gear oil, because this might in the long run (I think it will take years) destroy your synchromesh mechanism! There are a few (2 or 3) gear oils that are compatible with the materials used in the old synchromesh parts, but even here in Europe they are hard to find. So, better you use ATF as Mercedes-Benz says in the handbook.

All the time we are talking about the gearbox, not the transfer box. Right? Because the transfer box is quite another thing in case of gear oil. It needs hypoid gear oil, the same as in the axles.

Pirx

P.S.: Here is a photo of some (not all) types of gearboxes used in the 911 truck. The G32 is the one in the background. Easy to recognize, I think. Watch out for the square ribs on the lower part of the housing.

[nessie]

Many thanks for you quick reply.
Our mechanic has told us that all the MB trucks over here use gearoil- John Deere HY-GARD transmission and hydrolic oil- because this is better for the high temperatures here. Could this be the gear oil that is hard to find in Europe? (Our gearbox is the G32 type.)
The engine starts to go back in within the hour - so wish us luck!
Dave

[Pirx]

Hi David,

I don't know the John Deere HY-GARD gear oil. It is definitely not one of the mentioned oils.

I couldn't find out anything about this oil until now (and I can't spend much time for that) except that it is a so called UTTO oil. This is a special kind of oil for agricultural tractors that can be used for the engine, the gearbox (very special in agricultural tractors), the axles and for hydraulic purposes.

In the past, we had discussions about the use of such an oil in our trucks, but I think nobody dared to try out.

Pirx

[nessie]

thanks for the information you have been great help to us!
All we can find out is that the UTTO oil can become thin with age, but we will be servicing and doing oil changes regularly, so it shouldn't be a problem for us.
Let us be the 'test' vehicle for this oil and we will let all allrad readers know what happens........
Dave

[Jan]

Hi,

Regarding the piston rings, the fume could be a blown head gasket as well. If it is the head gasket there is often white sludge in the oil filler and gas and oil coming up in the radiator while the engine is running. One way do check for leaking piston rings is to do a compression check, then squirt oil in the cylinder and do another compression check. If the compression goes up after the oil spirt, the piston rings are shot.

Cheers

Jan

[nessie]

Many thanks for your message.
We had to change the piston rings due to wear but our head gasket was okay. The engine is 90% in and should be completed tomorrow.
Maybe we see you in San Francisco sometime?!
Dave

[Jan]

No problem, are you driving up here? Just shoot me a PM when you arrive! Cheers Jan