TVR / Rover V8 big end failure
Discussion
OK guys & gals, simple question and not really how I want to introduce myself to the forum, but sh!t happens unfortunately!
I was out for a drive recently with a friend in my pre-serp
4.3 Chim and noticed an unusual noise underbonnet, so I stopped to have a listen. Sounded like maybe (hopefully) only a tappet, but a mile down the road it became terminal - engine still runs but loud knocking. I killed the engine straight away as obviously a big end has gone. So I'm wondering what the likely extant / cause of this would be - can I just have the shells replaced with rover / TVR items to get it going again or am I into a full bottom end rebuild and whats the likely cost? Not exactly flush with cash so I'm hoping to have this done as cost effectively as possible while still having a useable engine - any suggestions welcome!
I was out for a drive recently with a friend in my pre-serp
4.3 Chim and noticed an unusual noise underbonnet, so I stopped to have a listen. Sounded like maybe (hopefully) only a tappet, but a mile down the road it became terminal - engine still runs but loud knocking. I killed the engine straight away as obviously a big end has gone. So I'm wondering what the likely extant / cause of this would be - can I just have the shells replaced with rover / TVR items to get it going again or am I into a full bottom end rebuild and whats the likely cost? Not exactly flush with cash so I'm hoping to have this done as cost effectively as possible while still having a useable engine - any suggestions welcome!
Sorry to hear that, I’m just having mine repaired at the moment, mine was due to the cam bearings moving causing a drop in oil pressure to the crank, mine has been going for a while so its a engine out job as the crank needs a grind, I’ve been quoted about £1900 inc vat etc.
How many miles has yours done?
How many miles has yours done?
Sorry to hear that jane, HOPEFULLY you killed the engine in time to get away with a plus ten grind at the minimum which if that is the case should cost around £900 to sort it. The main cause is the oil pump is just not effeiceint at high rpm the rule of thumb is 10 psi per thousand revs which can be acheived with the rover but anything less and it realy is a matter of time untill you have to spend, before you go ahead with work mail me if you want.
I changed the shells (big end and mains) in my 350 without removing the engine - it can be done as long as the sump can be removed with engine in the car.
However they did need changing (low oil pressure) and they did not make any untoward noises. The oil pump pressure relief valve is prone to stick which means there is no oil pressure at startup as the pump is not self priming. If the crank is knackered there is a good chance the camshaft will also have suffered.
You may try dropping the sump to do a cheap diagnoses - but be prepared for bad news!
However they did need changing (low oil pressure) and they did not make any untoward noises. The oil pump pressure relief valve is prone to stick which means there is no oil pressure at startup as the pump is not self priming. If the crank is knackered there is a good chance the camshaft will also have suffered.
You may try dropping the sump to do a cheap diagnoses - but be prepared for bad news!
Hi jane as danny says you can change shells just by removing sump the first ones to check are journals 5 and 6 they are always the one's to suffer as they are fed last by the left lifter gallery and there is allways a lack of oil by the time it get's there, hopefully tho won't be to serious hey!
Rob x
Rob x
If you do the spanner work yourself you can get a crank regrind much cheaper than 900 quid! when I did mine it was 8-10 quid / journal and about 50 quid for a full set of mains and big-end shell.
Check over the oil pump as they're not too clever and the the pressure relief valve is prone to sticking, if this the case replace the front cover and fit new gears and hand cover about 30 quid with new gears about the same.
Finally on a lighter note it may not be the big-end as the hydraulic lifters can also stick and produce large clearances, also its not unheard of for the rocker arm to break up and produce loud noises.
Best of luck
Matt
Check over the oil pump as they're not too clever and the the pressure relief valve is prone to sticking, if this the case replace the front cover and fit new gears and hand cover about 30 quid with new gears about the same.
Finally on a lighter note it may not be the big-end as the hydraulic lifters can also stick and produce large clearances, also its not unheard of for the rocker arm to break up and produce loud noises.
Best of luck
Matt
Nothing so drastic.
I dropped the sump, the bigs ends are easy - just undo the 2 nuts on the bearing caps of each conrod and you can move the piston stightly to change the shells.
The mains are slightly more tricky. I removed the caps one at a time and used a piece of plastic cut from a bit of electrical trunking to push the top half of the bearing shell out from between the crankshaft and block. A gentle tap with a hammer helped to move them.
You could do the job in a couple of hours if it all goes smoothly.
You will need to re prime the oil pump before starting
Danny
I dropped the sump, the bigs ends are easy - just undo the 2 nuts on the bearing caps of each conrod and you can move the piston stightly to change the shells.
The mains are slightly more tricky. I removed the caps one at a time and used a piece of plastic cut from a bit of electrical trunking to push the top half of the bearing shell out from between the crankshaft and block. A gentle tap with a hammer helped to move them.
You could do the job in a couple of hours if it all goes smoothly.
You will need to re prime the oil pump before starting
Danny
or you'll be doing it again
Knocking indicates big ends, like you say. Main bearing failure makes a low rumbling noise. Could be other causes though, so get a proper diagnosis.
The noise indicates a sizeable gap, which is unlikely to have left the crank unscathed. The crank and cap are being hammered out of round along with that knocking noise. Don't run the engine any more than necessary to diagnose the problem.
Big ends can, theoretically, be replaced if you take the sump off, find the one causing the noise and replace the bearing (and cap). You'll soon find out if there was a secondary cause for the failure. There will be a big difference in the cost of this (<£300) and of doing it properly, but you run a high risk of wasting £300 if the problem reappears soon. Whether that risk is worth taking in light of the i.r.o £2000 bill to do it properly first time is your decision.
At least check for scoring of bearing surface and roundness before wasting a bearing and more oil. I doubt any engineer would condone, or even agree to do such a dodgy job for you though. They would be aware of potential critiscism for sending you away with a £300 bill and a car that doesn't get you home. I would be concerned with why it failed in the first place.
How long since your clutch was replaced? - might consider at least killing 2 birds with one stone so to speak?
I hope it's not as bad as you fear.
Andy
The noise indicates a sizeable gap, which is unlikely to have left the crank unscathed. The crank and cap are being hammered out of round along with that knocking noise. Don't run the engine any more than necessary to diagnose the problem.
Big ends can, theoretically, be replaced if you take the sump off, find the one causing the noise and replace the bearing (and cap). You'll soon find out if there was a secondary cause for the failure. There will be a big difference in the cost of this (<£300) and of doing it properly, but you run a high risk of wasting £300 if the problem reappears soon. Whether that risk is worth taking in light of the i.r.o £2000 bill to do it properly first time is your decision.
At least check for scoring of bearing surface and roundness before wasting a bearing and more oil. I doubt any engineer would condone, or even agree to do such a dodgy job for you though. They would be aware of potential critiscism for sending you away with a £300 bill and a car that doesn't get you home. I would be concerned with why it failed in the first place.
How long since your clutch was replaced? - might consider at least killing 2 birds with one stone so to speak?
I hope it's not as bad as you fear.
Andy
Gassing Station | Engines & Drivetrain | Top of Page | What's New | My Stuff