After the rebuild..

[mental]

I'm in the UK, this is my first posting so a big 'hello' to everyone across the pond.

I have recently had my 2-litre 4-cylinder Rover engine rebuilt to a fast specification with uprated components. This was run in correctly on mineral 20w/50 oil, changed after 20 miles, then Millers running-in oil to 500 and standard 10w/40 to about 4500 miles. This is a turbo-charged unit and as expected, the ol' turbo died a sad death on just mineral oil.

After the funeral, a new ball bearing turbo was fitted for which the manufacturer insists on a fully synthetic and ester based oil. Accordingly, I am now using Silkolene Pro-S 10w/40

Now, here's the problem!

I seem to have blowby and poor compression on No. 3 cylinder. I suspect that despite the rebuild (about 10,000 miles ago), it may not have bedded in correctly and as a consequence, seems to be using about 500ml of oil every 800 miles. I can't obviously use mineral oil to bed it in further as the new turbocharger won't take it. Silkolene Pro-S has such good anti-wear capabilities that any wearing-in will take ages so apart from just carrying on and hoping that it will bed in better over the next 10,000 to 20,000 miles, I don't know what to do. Despite the blowby, the car dives very powerfully and smoothly with no apparent loss of performance.

I assume that there is no oil that will allow the rings to bed in faster but is fully ester based and harnmless to the turbo (a small Garrett-based GT25R, up to 130,000rpm).

Is there an additive that may help or perhaps a 'halfway house' in the oil department? I'll try whatever is needed as long as the turbocharger remains unharmed.

Thanks in advance for help and advice.

Mental, London

 

[mazduh30]

Did you have a leakdown test done? More accurate method of locating low compression problems. You'll be able to pin point wether it's the rings(air escaping through oil cap hole), intake valve(through the carb), or exhaust valve(exhaust pipe). If it's the valves....possible carbon/junk build up. Try using Auto-Rx, read the website in the sponsor forum section. It depends also on the precentage loss between all cyclinders wether you have a big concern or not. I know of no "additive" that will make mechanical problems go away.

 

[KW]

Very good advice!

If I read your post correctly you have over 4500 miles on the car now. Even chrome rings would be seated, moly rings will seat basically at start up.

500ml of oil every 800 miles is not that bad even though I'd be PO'd if I had a new motor that used that much oil.

Just a thought. Are you possibly over filling the crank case.

 

[Mitch Alsup]

Question: Were the cylinders rebored to clean up the roundness of the cylinders and then new pistons chosen of the appropriate size for the new cyclinder dimensions?

 

[mental]

Thank you all.

Mazduh30, I will have a leakdown test when I next visit my engine management guy in a couple of weeks. If it is the head then this will be done but this was part of the rebuild. It was skimmed 18-thou and rebuilt with a bit of mild polishing and new tri-metal steel gasket. However, AFAIK, the valve stems were not replaced.

KW, I can live with using a bit of extra oil and even though it has bags of power (265bhp/275lbft torque in a 1 tonne FWD car), I'm just concerned that despite the careful rebuild, something just isn't right.
Oil refills are done carefully, never overfilled.

Mitch A, the standard bore size is about 84.5mm and this was re-bored to 86.0mm, about the largest that one can go in these engines. This was done professionally by a reputable company in East Anglia that did a lot of work for MG Rover. The cross-hatching was clearly visible and the pistons were new 'forgies' from JE Racing, fitted by an friend of mine who is experienced at this. However, I have asked him if there were any problems during the fitting and he has categorically stated that there were none.

Thanks to all for ongoing help. The leakdown test may reveal more.

 

[ikeepmychevytoo]

How about consulting JE Racing about the thermodynamic correction properties of those "forgies" in comparison to the stock ones? May be some deviation from the standard is expeced as far as it is within the reasonable limits. Neither your consumption nor the performance sound like a complaint. I'd nonchalantly say if oil is too good then just drive harder, but after 4500 miles it'd odd to re-seat the ring anyways, synth. or boring fluid.

BTW, the engine when I drove a Rover 220 was probably just this in stock form. Well, I guess how bad it could be

 

[mental]

Ikeep, this is something that I had considered a while back. I took it out last night and the performance is certainly there but I did notice signs of 'exhaust blow' when the loud pedal hit the floor.
I have a couple of good engineering friends with far more knowledge than I. They agree that there is a possibility of the block actually distorting slightly under force. The boost level of the turbo is set at a relatively modest 13.5psi, soon to go to about 15.5psi but with the additional fuelling with the Emerald M3D engine management system and ERL water injection, this should take it.
I have tried to contact JE in the USA but find them difficult to deal with. Their UK representatives are a small firm that don't really offer much tech assist.
Many thanks

 

[mental]

Now had a chance to do more research on this.
It seems that it uses more oil at a low speed than when giving it serious right-foot-down action. I did a hard-ish 250-mile run over the weekend and it used very little but after a slow-ish 60 miles about a week ago, it used about 100cc! Strange!!

Therefore, I suspect top end (possibly valve guides)rather than rings. Is this suspicion logical?

Thanks again for ongoing help, chaps!

 

[mental]

Anyone able to confirm this?