Gti6 Big End Bearings

[Flying205Nutter 4]

I need help and advice. Destroyed the big ends and spun a bearing on my first 6 engine, put in a lovely low mileage engine and 800 road miles later checked the bearings and they where showing wear. Running silkoline pro s fully synthetic.

 

 

Put in the lead copper ones and 2 wet track days and 400 miles on road they are scrap.... Running mobil Mobil 1 SUPER 3000 X1 (rarely went over 5000 rpm)

 

 

Also I found this in the sump, where the hell has that come from?

 

 

The car has always been warmed up and cooled down properly. engine is standard with the addition of a 16 row oil cooler with thermostat. Has never knocked or tapped.

 

Photos.

 

 

[Anthony 1,003]

Did you check the clearances with plastigauge or similar when you fitted the new shells?

[Flying205Nutter 4]

Sadly not, this will be my next move, this engine has done 39,600 miles and has been serviced 9 times so I assumed the crank would be ok. Going to buy an oil temperature and pressure gauge so I know the oil is doing what it should.

[allanallen 528 2 Cars]

Were the original shells knackered the same?

[Flying205Nutter 4]

Were the original shells knackered the same?

 

Well you can see them in the first 2 photos, they where worn but not as badly, but i am paranoid after my first engine failed. I took the original shells out as I could see the flecks of aluminium in the oil. I took these shells out to check, oil was still clear of bits. Just don't know what I am doing wrong, had the 8v in for years and gave that death, then put an mi16 and never had a problem.

 

Has to be either oil pressure or oil temperature? but my dash is reading normal. oil pressure about half(when driving) and temperature just hits the 2nd mark on track.

[allanallen 528 2 Cars]

Gottcha. The photos are pretty crap on my phone but the first 2 pics look fine. The others look like they've been running tight rather than starving?

 

Daft question but what size bearings are you using? It seems to be an issue with the bearings rather than an oil problem seems as there was no problem before.

[Flying205Nutter 4]

Ok, so you think my old bearings are ok? The bearing size is standard. crank has never been out.

[allanallen 528 2 Cars]

From the pictures they look ok to me, not shiny or anything

[Flying205Nutter 4]

Shiny in places will try and get take some better photos.

[JeffR 51]

Are you certain the bearing caps haven't got mixed up or new rod bolts fitted (where running clearances must be checked?)

 

My attitude with engine work-'assume nothing, measure everything!'

[Flying205Nutter 4]

No, fitted them my self one at a time no chance of mixing the bearing caps up. didn't use new rod bolts.

 

All 4 cylinders are showing equal ware. the bearings in the first 2 photos where fitted in the factory.

[Flying205Nutter 4]

 

Best photo I can get, cranks has definitely polished it. I am now thinking the oil is getting too hot even with a 16 row cooler.

 

Going to platigauge it, fit new bearings and buy a reliable temperature gauge. Problem is if the oil is getting too hot, Why and what can I do about it?

 

 

[Flying205Nutter 4]

Right, oil temperature. checked the gauge and the sender. On Track it maxed out at 95c and on gentle road use its 75c.

https://www.dropbox.com/s/ermmsru1ge1ub3z/2014-10-19%2015.03.40.jpg?dl=0

https://www.dropbox.com/s/vlqkreq5jo6y1nx/2014-10-19%2015.03.57.jpg?dl=0

 

Oil pressure I checked with my air compressor. Engine runs at 2.5 bar at hot idle and 6 bar when the revs are up. I know this is not 100% accurate but it should be close enough.

https://www.dropbox.com/s/93cwp60cr33hvln/2014-10-20%2016.15.44.mp4?dl=0

 

Now the Plastigauge, I used the old set of bearings (factory) as they are only very slightly worn and did not want to buy a new set yet in case I needed oversize with a regrind. Now I think it reads 0.045? certainly between 0.038 and 0.050

 

Plastigauge looks angry....

 

 

 

What do I do now...... another set of bearings? I have another engine I can through in, lucky number 3? Or try something else

[Tom Fenton 1,541]

To be honest there doesn't look anything wrong with them to me. Yes they are used and show some witness marks but only really what you would expect to find. They are not badly scored or with lumps of bearing metal missing. Why do you think you have a problem? Is the engine knocking from the bottom end? Has it lost all oil pressure when hot?

[wicked 103 3 Cars]

Remove the main bearing caps next to it to check if the oil feed is not blocked by a swapped main bearing (no hole) or a blocked feed in the crank.

[Flying205Nutter 4]

To be honest there doesn't look anything wrong with them to me. Yes they are used and show some witness marks but only really what you would expect to find. They are not badly scored or with lumps of bearing metal missing. Why do you think you have a problem? Is the engine knocking from the bottom end? Has it lost all oil pressure when hot?

 

I am no expert but they should not wear, Yes I am paranoid now but when you can see the little silver flecks in the oil I don't think that's normal?

 

Has never knocked or lost oil pressure.

 

Best photo I can get

 

[Flying205Nutter 4]

Remove the main bearing caps next to it to check if the oil feed is not blocked by a swapped main bearing (no hole) or a blocked feed in the crank.

 

Will have a look abut I am wearing out all 4 big ends evenly, how do I check for a blocked feed in the crank?

[allanallen 528 2 Cars]

Have you plastigauged the bad shells or just the originals?

[Flying205Nutter 4]

Have you plastigauged the bad shells or just the originals?

 

Just the originals, funny I thought of doing that about 5 minutes ago, will do it over the weekend.

[allanallen 528 2 Cars]

The originals look fine IMO, the problems with the others. Why not put the originals back in? If you've got a spare engine anyways what's to lose!

Edited October 23, 2014 by allanallen

[Tom Fenton 1,541]

Have you checked the mains? Have you checked the cam journals in the head?

[wicked 103 3 Cars]

Will have a look abut I am wearing out all 4 big ends evenly, how do I check for a blocked feed in the crank?

If they wear out on all 4, then it is not likely to be a blocked oil feed.

[Flying205Nutter 4]

Have you checked the mains? Have you checked the cam journals in the head?

 

Mains look fine, They looked fine in the last engine which had spun a bearing.

 

Not checked the cam journals but if they are worn/wearing then the engine is scrap, thats why I have engine number 3 waiting.

Edited October 23, 2014 by Flying205Nutter

[allanallen 528 2 Cars]

Stick the original shells in and carry on

[Flying205Nutter 4]

Well the second set of bearings plastigauged at 0.045mm so taking your advice I will leave them is and see how it goes.

 

Can someone tell me what is the tolerance on the big end bearings?