Hi all, i'm hoping someone has some experience of rebuilding a V6 2.7 S Type Diesel engine.
Ill keep it quick, I was offered this car which is in remarkably good condition but just has an engine problem.
I thought 'Summer project' and proceeded to start the strip down. so I removed the engine & gearbox as one unit which was ok until the plastic sump on the gearbox got damaged (oh well)...
to cut a long story short I have now stripped the engine and found 5 of 6 con rods are bent, deflection of between 2 to 3mm from crank end to piston end.
has anyone else had anything like this or any information on what may have caused it? as far as I can tell there have been no issues with fluid in the cylinders (although I have not spoken to the previous owner as I bought from a garage) the main bearings are all ok showing little sign of wear and just normal wear showing on the big end bearings.
one thing I did note was that the main bearing nearest the gearbox has thrust bearings however only half of one on one side (see image) initially I thought this may have been the cause but apparently they are sent out of the factory like this!



Any help / advice gratefully received.

 

The diesel variant of the S-Type was never sold in North America and most of the members of this forum are from this part of the world. Have you tried posting on the UK or Eire sites?

Based on your description, connecting rods are usually bent from a hydro-lock situation as fluids cannot be compressed. Did you find evidence of water, or other fluid contamination in the sump or air filter?

 

Thanks for the reply, there was no evidence of any fluids anywhere which is why I am so confused, 5 of 6 rods are bent and just seems no good reason for it, i thought this was the UK site!

 

That is confusing as rods are usually bent whilst compressing coolant, or water that has been ingested through the inlet manifold.

Is there any evidence of discolouration on the connecting rods?

What is the condition of the cylinder bores?

 

One other possible cause of the distortion could be movement of the crankshaft. Is there evidence of damage to the block castings near the main bearing journals?

Has the flywheel or flex plate been touching the block casting?

 

the cylinder bores are unmarked and in very good condition, no damage to block and flex plate hasn't been touching the block at all either, there was a little bit more end float in the crank than i would have expected but would guess around .3mm (not sure what the limit should be) hence my question about the thrust bearing.

 

Same engine is in other makes & models so maybe a non-jag site would be more use.

 

I can't imagine anything other than fluid ingestion being the cause.

 

Since you are essentially going through the bottom end of the engine, it may be best to renew the crankshaft main bearings and inspect the clearances against specifications if there is no evident wear to the crankshaft journals. If there is excessive clearance, then either oversized bearings can be fitted, or the crankshaft replaced/reground to achieve the correct clearances.

It may also be best to replace all six connecting rods along with the big-end bearings and gudgeon bearings. If the gudgeon pins have the correct float, they can probably be reused along with the pistons. Of course, new piston rings would be a good idea as well.

 

Or maybe two injectors stuck open , it will be hard to find diesel fuel mixed in the oil . That's were I'd be looking . If it wasn't coolant or a major splash of water in the intake .

 

These 2.7D engines are known for diesel in the engine oil when they have a DPF regen that fails.

Various things break...

 

Since five of the six connecting rods are distorted, and while nothing is impossible, the likelihood of five injectors failing is slim. Plus, the amount of fluid drained from the sump would be substantial and cause the cylinder bores to be well washed. Having an over fueling condition would also cause excessive exhaust smoke, but there is no mention of that being the case.

One other possibility that comes to mind is contaminated fuel, but even that would not likely cause five rods to distort.

 

My bad I miss read that (5 of 6 ) I thought (5and6 ) . Yes a lot less likely . Damn my education !

 

I have had the crank checked and measured and all is ok, not much wear at all, the main bearings look ok too, the big end bearings show signs of wear but no scoring or any contamination just general wear. the oil level was normal before I drained (max mark on dipstick). the car was not smoking at all... is it worth / possible to get the injectors tested?

 

ive just been reading an article on these engines and it seems there is a failure mode which seems to fit with my damage profile...
'This damage to the engine is happening as result of turbo charger fault. Leak of oil from turbo charger to the inlet, build up of oil level in the inter cooler and finally surge of oil to the engine makes the connection rods to bend'
I only noticed by accident that when I removed the intercooler there was some oil in there as some of it ran out as it was moved. I guess I should check how much oil is in there as im guessing there shouldn't be any at all?

 

You are correct in your assumption that the intercooler should not contain oil. If this is a common fault, are there uprated turbochargers available for part exchange that can be fitted to prevent this from happening again?

Did you notice oil in either of the turbocharger housings?

 

No oil in turbo chargers, luckily a friend of mine used to work rebuilding turbo chargers and he had a look at them both and they are both in good order, he checked the clearances and all are ok with no sign of damage or leakage. so im really still at a loss as to why it happened...
anyway the new conrods arrived and new big end bearings so I have started the rebuild, just to compare straight conrod and bent conrod:

 

Just out of interest does anyone know how I setup the timing on this, when I stripped the engine I stupidly assumed the front pulley was on some kind of spline or keyway so that it would only go back on in 1 position (and also there was no way of getting to the crank shaft to mark it directly) so I marked the pulley at TDC and of course when I removed it there is no spline or key!! (I guess its on a taper which stops it from rotating) but of course now I have no idea how to find TDC for the crank!!

 

The procedure is most likely outlined in the Workshop Manual, which should also show how to determine TDC for the no. 1 cylinder.