Thread: 300tdi as an interim engine

Originally Posted by rick130

@ 300,000km I'd do the big ends, and particularly if it's a late '98 version it's imperative IMO.

Easy to do, too many are through the overlay at those km, and the late '98 version shells are really suss IME.

Yes - have been following the late engine big end issue.
Hopefully this new one's OK as its a '94, but the big ends were main reason for pulling the sump to at least have a quick check.

Dave's suggestion to rip the head off the dead one and go from there for starters sounds better the more I think about it. Couple of hours labour and no $$$ to have a look, and will have to disconnect most of it anyway if I'm swapping engines.
The dead one IS a late '98, so will be interesting what the bearings are like in that.

Steve

There's already a bit of history here, so rather than start a new thread I'll move on.

Finally got the 130 back to my place after being stored round at a mate's for the last 6 months.
Drained the coolant, and surprisingly there was quite a bit of it and it seemed nice and clear (bright orange colour) and felt very "coolanty". Doesn't really fit with a cooked motor.

To recap, the only info I had on the motor failure was from the mechanic who's yard it was stored at. "Motor's dead - pretty sure its bottom end"....

Pulled off the rocker cover and cranked it over to check if the rockers were moving (in case it was just busted timing belt). Yup - can see movement....

Then I noticed the 3 broken rockers !!!

So the timing belt hasn't broken as the rockers were moving, but possibly jumped a few teeth??

Pulled the head to have a look for other carnage.




Bores look reasonable (no wear lip or scoring etc), and pistons have slight marks from the valves. Is that normal?
Also, #3 piston has a bit of carbon buildup, whereas the others are pretty clean with just a bit of soot. Any ideas on the likely cause of that with these engines?

Steve

Its dropping compression on number 3 and the timing belt has skipped a few teeth.

so long as the deck is flat within 5 thou and the depressions in the head dont line up with the depressions in the block grab the fattest head gasket and go again with a new timing belt kit and do a full manual retime of the engine.

The TDI is a square interference design so a timing failure in about 50% of cases results in just busted rockers and squished lash caps.

A further 20% will bend the push rods which is typically diagnosed when they punch through the rockers from not rotating or when you cant get the valve lash to stay the same.

20% will bend valve stems and get sticking valves or excessive valve play and become either/both of smokey and compression loss through the valves. This 20% will develop on into the final 10% of engines over time if not repaired.

The final 10% bend a valve so badly it punches the piston at an angle and either snaps the valve head off or ruins the piston. They also tend to fracture the head around the valve seat.

My advise, unless your on the side of the road and just need to get it to limping on low power just to get it onto a trailer/home/to where it can be recovered, Remove the rockers and shaft, once its out pull the rods then check the valve play and guides (pull the spring, pull the stem seal and DTI for sideways movement and check for off center rotation of the valve stem, it can be done without removing the head) if they are not withing tolerance or are rotating off center pull the head and rebuild it.

IF the valves are true and in tolerance check the rods for length, straightness damage to either the cup or ball, using long cotton buds clean the seat of the cam follower and ensure that it is not visibly damaged.

If all that is good, inspect the rocker shaft, if its not stepped, bent, scored, bowed or cracked replace the rockers and the lash adjusters (they will have deformed threads and will be a pain to adjust) then reassemble the engine.

Occasionally, the rockershaft towers will have been deformed but I havent seen or heard of that occurring without obvious damage to the rockershaft.

Originally Posted by blue_mini

Unless you need to replace the sump gasket i wouldnt bother checking big ends. Id get a compression test, low coolant sensor and get the radiator fixed up and make sure the cooling system is A1.

Pretty much as many jobs that i can get done for under $200 and half a days labour.

Sorry no sump gasket on the 300 Tdi gasket goo , Id do the bigends timing belt but your onto that now

Bit more progress tonight.

Pulled the timing belt cover off after making up a flywheel locking pin and puller for the harmonic balancer.
Belt is still in one piece, but was really loose. Bottom of cover was full of broken plastic bits from the outside of the small idler pulley (one closest to the IP). Both idler pulleys are very dry and the one that the outside has departed from feels a bit "catchy".
I'm guessing that the pulleys weren't replaced with the last belt change. Why anyone would risk that for the sake of < $200 when you already have everything apart is beyond me.

Head and block both seem flat when checked with a straightedge (can't get a 3thou feeler gauge under). Next thing is to get hold of a valve spring compressor and pull the valves out to check them.

Steve

Stripped the head and all the valves are still straight.

The valves on #3 are slightly pitted, which might explain the carbon buildup that Blknight suggested was low compression.
Pulled the piston from #3 and the second compression ring was stuck, so not sure which came first...

Since this was a '98 build engine, I always intended to pull the sump and check the bigend bearings (sump needed resealing anyway).

See for yourself:





298K km's on this engine, so another one for the ~300K bearing failure list....

Thankfully the crankshaft still looks perfect.

Also checked out the cam followers as per suggestion ealier, and 2 of the bronze followers have slight deformation around the pushrod hole. Rest are fine.
Then spent an hour learning the lesson of "don't let the follower roller drop out of the housing and down under the cam". Won't make that mistake again in a hurry

Steve

Originally Posted by steveG

Stripped the head and all the valves are still straight.

The valves on #3 are slightly pitted, which might explain the carbon buildup that Blknight suggested was low compression.
Pulled the piston from #3 and the second compression ring was stuck, so not sure which came first...

Since this was a '98 build engine, I always intended to pull the sump and check the bigend bearings (sump needed resealing anyway).

See for yourself:





298K km's on this engine, so another one for the ~300K bearing failure list....

Thankfully the crankshaft still looks perfect.

Also checked out the cam followers as per suggestion ealier, and 2 of the bronze followers have slight deformation around the pushrod hole. Rest are fine.
Then spent an hour learning the lesson of "don't let the follower roller drop out of the housing and down under the cam". Won't make that mistake again in a hurry

Steve

steve, that is a textbook 98/99 set of big end shells at 250K +...

i am glad to say it seems i am right to suspect these late engines, seen quite a few like this now.

jc

Obviously I'm up for a few parts now to even put it back together, but after some guidance from you 300tdi gurus as to anything else I should be doing while its all in bits.

Here's the definite list so far:

• New big end bearings
• New timing belt and pulleys + front crank seals
• Replace broken rockers/adjusters
• Replace bent pushrods
• Head and manifold gaskets
• P gasket
• New hoses

The head needs a freshen up. Is it economic to get a quick valve grind done and new valve seals etc or does it rapidly become cheaper to get a replacement head?

Pistons - worth removing the rings and cleaning out any carbon buildup (or replacing rings) or best to leave them alone?

Worth replacing the cam seal while I'm in there?

Anything else I've missed?

Steve