Engine rebuild failure x 2

[kingkenny100 0]

Hello,

 

Fairly new to the forum although have used to for spares over the years. Having major Corrado issues and now reached breaking point! It’s quite a long saga so apologise for the long post.

 

3 years ago my VR6 engine went wrong, the tensioner went and I decided to rebuild the whole engine with a mate who has rebuilt several VW engines but never a VR6. It seemed a great idea at the time and I thought would make the car bomb proof for the future.

 

The rebuild done, new chains, clutch, piston rings, oil pump, big ends the lot. I kept the car in a garage until spring then started easing in the miles. Whilst in storage I replaced disks and pads and even treated it to SS exhaust.

 

However at 400ish miles…the engine went bang and was making a horrible metal clanging sound. It sounded like bottom end, but dropped sump and nothing looking out of order and I wasn’t sure how it could be. I checked the torque on the bolts I could access but they seemed fine.

 

I tried changing the head (someone suggested a possible blocked oil gallery) and also put in new tappets…partly as it was on the few things not replaced and the noise did sound a bit tappety. But the noise was still there and next time I checked the big end bearings I could see damage.

 

So engine back out this year and I got a new crank and a set of rods (from this forum) and new bearings. As well as new oil pump, bolts, gaskets etc. engine back in, sounded fine, booked in MOT. Changed an ABS sensor, new front calliper and all MOT ready. On the way to the garage, some 12 miles (slight detour) the noise came back. 100% sure it’s the same noise - the big end bearings. MOT cancelled. Car is now sitting back in my driveway.

 

I am gutted…it’s been a slow process and I have ploughed in too much money…but can’t figure how this can go wrong….twice. Once after 400 and once after 12 miles.

 

Would welcome any thoughts or suggestions. I am not sure I can bring myself to try and repair this again….so may have to consider selling. It is generally in good nic and has black leather….so also curious on a value of a corrado in this situation.

 

Thanks

[Jim Bowen 1]

I heard of someone else having a similar problem and they hadn't fitted the oil jets to the bottom end.

 

[VEEDUBBED 0]

...Well i have Got a 10.000 mile block, crank, mains, etc, etc up For grabs...

Sorry, i couldn't resist..

Oil galleries clean and blown out whilst you were rebuilding? Did you check the oil flow to the bearings? I use a modified starter motor with an old oil pump jack shaft welded on, Great For bringing up oil press. On a new engine. Crank oil ways all clear? Have you Got a mechanical oil press. Gauge fitted inside the car? Even an electrical version would suffice.

[kingkenny100 0]

Cheers. I don't remember the oil jets. Maybe something I never removed. Will look into this anyway

[kingkenny100 0]

Oil galleries should all be clear. Head, block and crank were all looked over and paraffin bathed by local shop. To get it up to pressure engine was turned without ecu connected. Oil gauge was fitted after first time. Was reading 5 bar when running, dropping to 4 as it ran in driveway. On my longer 12 mile run, was just under 4

[kingkenny100 0]

Well I took the sump of for a wee inspection. Some of the con rod bolts were very loose and one of the bearings had moved and is damaged. Crank looks fine though so I'm quite optimistic here.

 

Im just unsure why this would happen and what to do next. Any thoughts??

 

I am concerned about these oil jets as I don't remember them so might unbolt gear box and see if I can check they are there

[VEEDUBBED 0]

Begs the question, How the fuc were they tightened down in the first place?...

Check the crank really carefully now 'cos now that a bearing has spun god knows if it's scored the journals.

I'll have a peek within my spare ABV block For those oil spray jets, not that i can see those causing the problema you previously described.

Ask Your mate who did the rebuild if he angle-tightened the rod bearing bolts.

[kingkenny100 0]

It was definitely torqued and angle tightened. It seems suspicious this is the second time this has happened though. one potential is these bolts were re-used which I know is not great but they had only done 400 miles....although I'm not sure if this would cause the problem or if there is a deeper problem

[Dox 23]

one potential is these bolts were re-used which I know is not great but they had only done 400 miles....although I'm not sure if this would cause the problem or if there is a deeper problem

 

You'll never know for sure, but they're stretch bolts, made to stretch once only and then be replaced, personally I wouldn't have reused them as the potential cost far out weighs the cost of the bolts.