[Mk2] [Turbo] Suspect camshaft.....Bad News Its my Big End.....IM BACK BABY!

[Turbo Dragon]

Dear all,

Its been over a year since my last post and in that time my Turbo has done <1000 miles and been under wraps on the drive

Just gone through MOT fine and a couple of weeks later i noticed a really odd knocking sound, the tempo increases inline with the revs and it appears to be coming from inside the block.

Initial diagnosis of a mechanic is either cam bearings or camshaft is suspected.

Soooo im preparing myself for some bad news following further diagnosis soon, can someone give me a crash course in cams?

Is it worth upgrading, what to go for, wheres a good place to get from if it does turn out to be the shaft?

Trying to find a silver lining

Any advice greatly appreciated

My engine is following spec currently: 280 fly & 240 wheels

CT26 Hybrid
Apexi Power FC
Walbro Fuel pump
Sard FPR
Greddy I/C
Boosting to about 1bar

Other bits are
dumpvalve
leads/plugs etc.
Air intake
Decat and exhaust

I have also got an AVCR and 850cc Injectors waiting to go on.

Thanks for the time

[Martin F]

you can get the parts for next to nothing second hand, or even better still buy a rev3 turbo cylinder head and swap that with the gasket, kill 2 birds and all that

are you able to carry out the work yourself?

[Turbo Dragon]

Nope, not that mechanically minded.

I can manage fitting stereos and buying parts....just

Getting second hand cams is an idea, whats the benefit of getting Rev 3 cylinder head over the Rev 2 one?

Also is there a benefit in getting uprated cams? Any recommended?

Thanks for the time

[Bender Unit]

Its impossible to guess without hearing the noise but could it simply be that the head needs reshimming? Its it a tap or an actual knock?

Unless the camshaft has snapped I cant see how you would be getting a knocking sound and if it snapped the engine probably would run to great.

Just a thought though, what may sound like a noise from the head, could be coming from the bottom end?

[skip0pot2mus]

You sure the mechanic didn't say bottom end.. crankshaft and bearings?

[Turbo Dragon]

It hasn't been confirmed yet, i'm waiting on that.

I'm mearly trying to get ahead of the game, as the initial opinion was given by RAC chap who listened and said it sounds like the cam or bearings

Only basing it on that and trying to get a quick education on what they are and whats involved in replacing them.

Thank you for your thoughts, if its not possible for camshafts to knock then i guess i will have to wait until a more thorough investigation has been done at my usual garage.

[RobCrezz]

Has it run low on oil?

Hope he didnt mean crankshaft/ big end knock!

[Turbo Dragon]

I too hope my big end hasnt been knocking

Oil was fine last time i checked less than 500 miles ago and it hasnt appeared to be leaking.

I think im still playing the old waiting game for now

[Bender Unit]

So the car didnt actually break down then? You just heard the tapping noise and called the RAC? Can you hear this noise from inside the cabin? Or just when you have you head in the engine bay?

I am certain that if it was the bottom end on its way out the RAC guy would have known.

[Turbo Dragon]

Exactly, car still drives. Just started making a racket so stopped to avoid further damage.

You can definately hear it from within the cabin when the engine revs the speed of this noise increases. It is a metallic knocking sound, i initially thought it was something like the exhaust manifold banging but on further examination the sound is not coming from that area

It is a lot louder within the engine bay and sounds like it is coming from within the block.

Cars going in on tuesday so hopefully should have a clearer idea by then

[ashley]

when the engine revs the speed of this noise increases.
It is a metallic knocking sound
sounds like it is coming from within the block.

Hate to say it but that does sound like a bearing

Good luck getting it sorted buddy

[Turbo Dragon]

Out of interest if it is a bearing, is that a big job to repair?

Can it damage anything else with it, is so what is likely?

And are bearings or things around them upgradeable?

Sorry for the dumb questions, engines aren't my strong point.....



I found a Haynes manual for a '74 Ford Capri once that shows pictures of internals and it scared me

[ashley]

A speacialist can change the bearings by dropping the sump, so potentially not a huge job- not sure how much £££ your looking at.

'Upgrades' tend to be bearing made of a slightly softer material and are used in high spec engines to ensure that if anything is going to give its the bearings and so protecting other engine parts. At least that's what I've seen on other engines in the past, happy to be told I'm wrong with 2's!

If you keep running it with a bearing gone you risk it seizing and sticking a con rod through the engine block - basically scrapping the engine.

I had a bearing go on a honda engine and we had decided to scrap the car (was the 3rd engine it had seen and it was time to do something new), as I drove out of the drive to goto the scrappy there was a loud bang and the engine stopped. I opened the bonnet and there was oil everywhere and a big hole punched in the side of the block...I never did find the piece of block that had been punched out!

That car knew it's time had come and threw one last tantrum...had to tow it to the scrappy after that

[Turbo Dragon]

Finally got my regular mechanic out to my house to have a listen as i fired her up a couple of weeks ago and the noise was horrendous

So started her up and he says.....'Turn it off straight away, thats your big end '

Whoops......so this is a bad thing i gather.

Im looking for a silver lining here, does it need a new engine or can 2s be repaired easily enough with the lump out? Is it worth doing anything else whilst its out?

From what I can gather the majority of cost would be labour, correct?

And finally, what cuases big end failure and what can it damage in the process?

Thanks a lot anybody, hope shes still worth it!

[mks2005]

the main thing that usually courses the big end to go is lack of oil..

Not too sure abotu the MR2s but i used to run mk3 supras and bottom end used to go on those all the time if you drove them hard... the main problem with those was the position of the oil pick up.. if pushed hard the oil would move to the back of the sump and the oil pickup could not get enough oil.. a good fix for this was welding a baffle nito the sump..


anyway i dont think the mr2s would have this issue...

But yeah if your going to get the engine pulled out you may as well get a full rebuild done, crank ground correctly, engnie cleaned out as bits of the bearing would probally have broke off and started moving aronud the engine.. so because of the that other damage can be done so its always best to check.


I have been told stories of mr2s having bottom ends go quite a bit not sure how true this is tho..

[GhostWKD]

the main thing that usually courses the big end to go is lack of oil..

Not too sure abotu the MR2s but i used to run mk3 supras and bottom end used to go on those all the time if you drove them hard... the main problem with those was the position of the oil pick up.. if pushed hard the oil would move to the back of the sump and the oil pickup could not get enough oil.. a good fix for this was welding a baffle nito the sump..


anyway i dont think the mr2s would have this issue...

But yeah if your going to get the engine pulled out you may as well get a full rebuild done, crank ground correctly, engnie cleaned out as bits of the bearing would probally have broke off and started moving aronud the engine.. so because of the that other damage can be done so its always best to check.


I have been told stories of mr2s having bottom ends go quite a bit not sure how true this is tho..

My first tubby had fsh, well cared for example etc, unfortunately big ends went on it 9 days into ownership it ended up sat in my flat parking for a while before being sold on ebay

[mks2005]

My first tubby had fsh, well cared for example etc, unfortunately big ends went on it 9 days into ownership [Sad] it ended up sat in my flat parking for a while before being sold on ebay [Sad]

then im guessing there msut be somthing in the design on the engine that courses this..

dont know enough about the 3s engnies yet LOL have yet to strip one down.. also not looking forward to the day i have to do it lol..

supra engine was easy to get out...

anyway to the orig poster im sure someone will be onsoon enough to let you know the details about the 3s engines and the best thing to do..

myself i would always go for a full rebuild if you can.. i went down the second hand engnie route with my supra as i thought it would be easier.. but in the end i had to rebuild that noe anyway lol.

[Turbo Dragon]

Cool, thanks for the info guys and the thought.....

I would prefer, I think, to rebuild mine because in the past few years iv changed loads of things on it and i guess its a case of 'better the devil you know'

Sooooooo IF it is possible to rebuild my engine, what is usually involved and what can be uprated/tuned whilst its being done?

Idea is that if for example bearings needed replacing then I would rather uprate than replace stock, simialrly for cams etc....

[JJ]

Have you established why its failed in the first place ??!

Usually contamination to the bearings ( initial build ), low oil level, crap oil, oil pump failure / lazy....

Theres also out of balance issues which is usually down the list of reason for failures if nothings moved / changed for a while...

Occasionally, depending on the time its been running / knocking... it can be servicable... the big end bearing is soft in comparison to the crank / rod.... "designed" to almost be the weakest link....

I've managed to change a couple of bearing failured engines through just taking the sump off ( they never drove it after hearing death knock )... if there is crank damage though... will require machining ... and if you're going down this route... advice...you're better off sourcing another engine as its more economically viable.

Any tips on a rebuild... on the rev 1/2 engines, you're in a good position to source the parts from the states cheap.. even at the current exchange rate... but you'll have to inspect that crank first.. or simply source another and buy all the rebuild items from the states...

[Turbo Dragon]

Thanks for the info, all the reading up on this seems to point to a lot of possibilities.

No idea why its failed, I heard it start knocking on a drive back from a show,and then hasnt covered more than maybe 20 miles?

Car done less than 3000 miles since its last oil and filter change so can't be sure at the moment I guess

Still feeling a little dazed about the whole thing really, am i right in thinking that the majority of cost for repairing would be in labour?

In which case It might be worth my while tuning up more than I originally planned to and doing more internal work?