Gto Newbie. spun bearing :/


Im a newbie to gto ownership and ive been loving it.
I bought a twin turbo 5 speed manual and its great.

However the other week i span a bearing. I had been running slightly low oil pressure and with abit of speed the engine started knocking and the bearing had spun.

I pulled the sump off and the conrod was knocking.
When i pulled the conrod cap off the crank wasnt overly damaged (in that i have seen worse)
I bought some new bearings and polished up my spun journal. It cleaned up rather well except it was 0.02mm excentric.
I made the decision to put it back together fully aware that it might spin again.
I also flattened out the sump.
I put in some heavy oil and it ran for a week.
Ofcourse it has span again.
I dont need the lecture about it… really. I knew it was probably going to happen.

Anyway. What im looking for is the permanent solution i need.
With the exception of buying another turbo engine (as i don’t really want to spend that much)

So… can i get a crank reground? I know you can buy undersized bearings… but i read that they are heat nitrate treated?(or something) (whilst im not a metallurgist) as far as im aware you cant grind them back?
As im aware there is the 2 different cranks, the cast pre93? (2bolt?) And forged post93? (4bolt?)
with regard to regrinding is there any considerations to be made between the 2?

My other option is replacing the crank.
I can get hold of a crank out of a non turbo. Which to the best of my knowledge isn’t spun… or is in as good as a condition as it needs to be.
Are they interchangeable? Between the N/A and turbo?

Please excuse me if im wrong somewhere with what i have said, but im only using info i have sourced off the net so far.

And ahead of any help or pointers i really appreciate your help amd input guys.


Easiest option is replacement engine , also we had a similar scenario with one of the guys at Japfest , @benh listened to that particular engine

Pretty much now you have spun the bearing you need to bin the oil cooler and anything else that contamination will have travelled through , unless you can guarantee getting all remaining oil and debris out of it

Other option is get yours rebuilt , for something that will last and be reliable there isnt really a cheap option , replacement engine is the cheapest but its an unknown risk unless you have an idea of its previous history

Craig :smile:

Welcome to GTOUK also :sunglasses:

Just to add another question, i got same thing on mine 3000GT. Its more like a rattle rather than knocking, this rattle is common when the engine i warmed up and is it rattles at some specific rpm, mostly under 3000. I dont know the history of the famous lash adjusters, but previous owner changed oil to thicker one and added additive and he claims that noise improved. Now the thing is if it is spun bearing, wouldnt i hear the rattle all the time, from cold to warm and any rpm? I got good oil pressure, over the middle when cold and at least 1/4 of the scale on the oil pressure meter.
And how on earth does these bearing spin anyway? Bad design?

Best regards

Th se verit y of a bearing spin can be minor or severe, but even a minor one is very bad news.
they will get progressively worse.
at the moment i cant hear mine at idle.
In my experience you tend to hear it when holding steady revs somewhere around the 3k mark. You dont really hear it when revving the engine up or down.
It does sound like a rattle to be honest.
the best method i would guess to easily check at home is to put a screwdriver on the block and put your ear to the handle if the screwdriver. If you can hear the noise as a knock through the screwdriver then its probably a loose conrod and a spun bearing. You should also find metal shavings in your oil however as the sump plug isnt the lowest part of the engine it might not drain metal shavings out.
If you arent sure what to look for then just take it to a mechanic.
as far as i am aware it happens from low oil pressure which can be from dented sump, which restrict ol pick up and causes low oil pressure.
fyi my sump looked fine from outside and i only saw the problem Dents when i took the sump Off

Dented sump is a result of bottoming out, not something is dents/deforms by it self right?
Well apart from the rattle my engine does not blow any smoke so it sort of seems fine. At this point i just hope it just famous lash adjusters and not the rod/bearing. Its not like i cant afford to fix it my self as i saved some cash to buy parts and stuff, but working on the engine seems like a nightmare as the engine bay is tighter that virgins lady parts.

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You have to take it to a mechanic and ask. There is no point in hoping it to fo away for you to push a conrod through the bottom of your engine.
I cant really afford a new engine myself hence why looking for another solution. You have to appreciate that these are expensive cars and they will cost alot of money when they want money spending on them. I knew it when i bought it and i have to accept my decision.
I dont think you can cheap out on it. It will only get worse. get it checked by a mechanic

As far as grinding a crank if it is just 0.02mm then you should be able to do that within tolerance. And nitriding is never that thin so you should be ok there. However it will take a very specialist machine shop so unless you have good contacts it wont be cheap. If you can get hold of a second hand crank and rebuild it yourself then that is going to be cheapest. If you are going to pay someone to rebuild it then it gets a lot more expensive. I can’t answer about differences in the cranks but i’m sure @GSXRKID will be able to tell you. I would imagine they are different…

I see what i can do with this screwdriver trick you mentioned and see whats what. Thankes guys.

My engine was rebuilt by previous owner had the crank re ground at drakes in Bradford has done 20,000 miles since and still perfect number 6 conrod had gone that time will dig out the bill and contact if you want ?

So if it is a bearing, how much things needs to be replaced? Crank and conrods? I`m gonna investigate my engine a lil bit closer to check lash adjusters and stuff to determite cause of the knock at first. God i hope its just the lifters.

As I advised above if you have spun a bearing you can start by binning the oil cooler , every oil gallery and orrifice will need thoroughly cleaning to get rid of any contamination from the bearing , this basically means stripping the engine down hot tanking etc , if you don’t do this the rebuild will be a time bomb waiting to go again . Quickest and easiest way to get you back on the road is a second hand lump then rebuild your own motor and future proof it with upgrades if you ever decide to tune the car . If you are in no rush and know the history of your engine then rebuild that

Craig :slight_smile:

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Agree that’s why It cost last owner of mine 2k to rebuild all new parts upgraded oil pump the list goes on,…would have been cheaper for second hand unit but a bonus for me :grinning_face_with_smiling_eyes:

That’s cheap dave!

All the machine work was professionally done but he was an engineer so did the rest to perfection by the looks of it from the bottom up seems fine although rob said some parts too cheap, but taking it in for a good health check Monday expensive but seems to know what they are doing

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This is some of the bills from drakes engine re manufacturing although bear in mind this was in 2009 when engine rebuilt but they do seem to have done a good job grinding crankshaft re sizing Conrod honing cylinders and used milled cylinder head along with all other parts like full gasket set and upgraded oil pump

I seen some videos on youtube about engine rattle and some of those causes was something loose inside the plenium/manifold. Is there something inside 3000GTs plenium that could be loose that could make the noise? I remember one episode of Wheeler Dealer where they restored a Boxter, and it had rusten heat shield which vibrated and made bad rattle.
Also maybe i just try with thicker oil, i think now i have 10W-40. Maybe go up a notch?
The repair manual of 3000GT sugests that engine noise from valves or conrod is due to thin or diluted oil.

Nothing inside the plenum on a TT , the N/A’s have a butterfly system that is electrically controlled that changes the length of the runners in the plenum though .

From the sounds of it best bet with your is get a mechanic to listen to it then go from there , it will prove very costly just changing or chasing parts

Craig :smile:

Well of course i gonna need to investigate stuff before repairing anything, anything else would be stupid. Just trying to collect all knowlege around the problem, maybe find something else that causing the problem. Just think how dumb it would be to replace the bearings and something else less complicated caused the rattle.


As i say you need someone to listen to it , it could be a collapsed or noisy lifter or it could well be big ends , unfortunately its one of those hard things to diagnose on the net .

No need to get defensive in your post , im trying to be as helpful as i can with your request , where are you based maybe someone local with a bit of knowledge of these motors could pop over and have a listen for you

Craig :smile:

You can’t run a Gto on the cheap unfortunately everything costs ££ people don’t realise that… The Ferrari of the 90s the scrap yard of 2015 it’s like abusing the wife they don’t do the washing after that (another drink then bed )