My Diesel Let me down!

[smithy010]

Ok, so i think i've decided not to buy one of Loon's TDI's.. The reason for this, is i think it will be too much rooting around, especially for my daily driver. If i had a functional engine, and could work on the tdi at my own pace, then i'd probably do it.

Just an aside, i think if i were to go TDI, i would try to keep the Electronic engine management..

Anyway, unless someone has a spare AAZ laying around, i'll be keeping the 1.5.

So i started it for the first time since i had to limp it home from pheasants nest. It was not really a surprise, but it ran quite rough (on 2 or 3 cylinders) for about 5 minutes after starting, then it started running fine. I think this is probably that the cylinder temperature came up and then it began to fire on all cylinders. Would this be feasible?

I'm trying to decide what to do next. Seeing i pretty much know it's buggered, do i dig up a compression tester before i pull the head off, or do i just bite the bullet and pull it down and have a look see?

Next question is where should i buy parts from? I guess i'll check out tooleys importers and see what sort of price they can do for me. Any overseas place that i should check out?

Getting sick of public transport.. want my car back!

[gldgti]

between tooleys and HSY imports you can get pretty much everything you need. prices arent bad.

[smithy010]

Well, in case you all want to know, i will be taking the head off the diesel probably tonight. Will send pics of what i find inside!

I'm guessing it will be interesting.

[smithy010]

Well, the head's off, but the pistons aren't out yet.

I reckon the head looks to be in pretty good nick. No cracks between the valves. There is quite a bit of soot buildup on no. 3 exhaust valve. Maybe this is the one that has issues.
The bores look ok. They are fairly glazed, but i guess this is to be expected. There is a little step at the top of the bore, but that's to be expected as well.

I'll take the pistons out soon, so i can see what's really wrong. I'm expecting cracked rings in one pot at least. Photos when it's light.

[smithy010]

Hmmmm..

Well, one thing's for sure, the rings are quite worn. The gap on them is about 2mm. Some more, some less. The bores are fairly glazed as well. The pistons look in pretty good shape though, and there are no cracked rings. But that's not all.

It's got some major wear on the no.3 big end bearing, which is disconcerting. It also appears to have spun. The thing that makes me think that's it's not my shoddy big end bearing job is that when i bought the engine, it had a spun no. 3 big end bearing as well! But then, it could well be a shoddy job on my part.

So my theory about why i suddenly got a stack of run-on and blowby issues is that it spun this bearing, and then started overheating as a result (due to the extra bearing drag). This could have brought on the blowby. Anyone think that's plausible?

So, where to now, a new set of rings and big end bearings and off i go again?

Also a question while it's on my mind, when i hone the bores (i haven't measured them yet, but we'll see), should i be dropping the crank out to stop filings getting into the main bearings, or is there a trick to keeping the filings out?

Ok. Well, i guess the only way to learn is to fiddle, and if anything, this is some of the cheapest fiddling i could be doing.

[Blitzen]

Hmmmm..

Well, one thing's for sure, the rings are quite worn. The gap on them is about 2mm. Some more, some less. The bores are fairly glazed as well. The pistons look in pretty good shape though, and there are no cracked rings. But that's not all.

It's got some major wear on the no.3 big end bearing, which is disconcerting. It also appears to have spun. The thing that makes me think that's it's not my shoddy big end bearing job is that when i bought the engine, it had a spun no. 3 big end bearing as well! But then, it could well be a shoddy job on my part.

So my theory about why i suddenly got a stack of run-on and blowby issues is that it spun this bearing, and then started overheating as a result (due to the extra bearing drag). This could have brought on the blowby. Anyone think that's plausible?

So, where to now, a new set of rings and big end bearings and off i go again?

Also a question while it's on my mind, when i hone the bores (i haven't measured them yet, but we'll see), should i be dropping the crank out to stop filings getting into the main bearings, or is there a trick to keeping the filings out?

Ok. Well, i guess the only way to learn is to fiddle, and if anything, this is some of the cheapest fiddling i could be doing.

While you have the engine out and apart you should drop out the crank and inspect your main bearings and crank while you are at it. The spun bearing could have damaged your crank in some way, so have a good look at it and get it crack tested. Depending on how many km the engine has done, you may as well throw in new main bearings too.

[cetane]

Smithy... is the motor still in situ? You'd have to pull it to remove the crank. It sounds as though the runaway has done a fair bit of damage and the safest way is to pull the motor, remove the crank and get it reground. It costs time and money but it's better than replacing the shells and reassembling then finding you've wasted your time. If you decide not to, inspect the journals for scoring and mic them to sure they're within limits then to be sure get some "Plastiguage" or equivalent and check for bearing crush. As for filings from honing, just get some kero and wash everything thoroughly after you've done it. I'd also remove the ridge and make sure the honing left a nice "cross hatched" finish. If it was my motor and I wanted to preserve the car (and I could afford it ) I'd get the crank done.

[smithy010]

Thanks for the words of advice cetane. I'm not sold on pulling the crank out yet.. It seems like it could make some sense though. The crank was replaced with a good second hand one 12 months ago. I know it was good then, and i plastigauged it then as well.. So it has had new main bearings about 10 000k's ago. Then, considering it did this to the big end bearing in that time, it may have done it to a main as well..

What would cause a big end bearing to spin on the same pot twice in a row? Just a fluke?

[VW Convert]

Thanks for the words of advice cetane. I'm not sold on pulling the crank out yet.. It seems like it could make some sense though. The crank was replaced with a good second hand one 12 months ago. I know it was good then, and i plastigauged it then as well.. So it has had new main bearings about 10 000k's ago. Then, considering it did this to the big end bearing in that time, it may have done it to a main as well..

What would cause a big end bearing to spin on the same pot twice in a row? Just a fluke?

I'd be checking the conrod out to make sure it is to tolerance. Can't really understand how the crank could be re-useable as is if it has spun the bearing, surely it would need to be mic'd and at least linished if not reground.

Cheers

George

[cetane]

It's usually caused by lack of lubrication, although if the big end cap wasn't torqued to the correct setting or replaced back to front there'd be the same result. Whenever I rebuild an engine I check each journal by tourquing it and then slackening off one nut. You should be able to get a 5 thou feeler in between the cap and the conrod. If the gap is too big, then the bearing will fail. If it's too small than it won't get enough lubrication with the same result. The 1.5D conrod is the same as the 1.5 petrol's so they can be swapped, so if there's any doubt I'd do it. Also, check the oil galleries in the crankshaft for blockages.