15 replies to this topic

[Curley]

Evening all, I have a 1293 A-Series that's done about 1800 miles since it was rebuilt. I did not build the engine myself and it's sat for 10 years before being run in this year. I recently changed the outer drive shaft oil seals, replaced the filter and filled it with new 20w50 Miller 'designed for Mini' mineral oil.

 

200 miles later the oil preassure light came on. I pulled over and checked the stick and NO OIL!!!! So I've filled it up again and light goes out. The thing is when I did a static compression test today I got 100 PSI on #4, 80 on #3, 100 on #2 and 90 on #1.

 

1) 100PSI sounds a little low to me??? Shouldn't it be more like 160-180+

2) Any common issues that could lead to low pressure on number 3 & 1?

 

I'm going to do a wet test tomorrow night to see if it's the piston rings or valve seats I so hope it's just the head!!!

Edited by Curley, 26 October 2014 - 07:07 PM.

[KernowCooper]

Be interesting what the wet test results are, did the engine not smoke heavly to use over 4 litres in 200 miles ?

[MIGLIACARS]

some thing strange
there it would smoke like **** if it was using that much oil, id be surprised if it ran at all.
 
did it not leak out,  
 
 if you didnt build it it could have been built for a turbo setup,   low compression
it does sound low but if its stopped using oil and its running nice and it pulls well!!!!!!!!!!!      what more can u want.
 
 
if the rings have gone that bad im sure u would see it smoke. have u checked the water make sure oil hasnt contaminated it!!!

Edited by Dan, 27 October 2014 - 07:49 AM.
Do not try to avoid the swear filter

[Curley]

No, that's what worries me. It blew a little blue ish smoke on start up but nothing while driving. Even then it's not a lot and nothing visable after the first puff. It is a leaded head which I run on super unleaded & an octan booster/lead replacement so I won't be suprised if it's the head. But i wouldn't have though they'd get that bad in 2K miles??

 

I can't see any obvious signs of an oil leak either - the car is parked in the garage over an old white cardboard box - and the gearbox case is dry as are the drive shafts and CV joints. There is a little oil from the gear selector but not enough to loose it all!!

 

100PSI seams a little low to me. If the rings are good shouldn't it be more like 160+?

[Curley]

if you didnt build it it could have been built for a turbo setup,   low compression

it does sound low but if its stopped using oil and its running nice and it pulls well!!!!!!!!!!!      what more can u want.

 

Could be - the car did have a boxed bulkhead but alas no turbo

 

It runs ok, We're not sure what cams in it but it on power nicely by 3Krpm. Fitted with a HIF44, 1.75" Maniflow, 1.5 rockers and produced 73bhp on the rollers @ SRE. From an early small valve A-series heads too :)

Edited by Curley, 26 October 2014 - 07:48 PM.

[Dan]

It was built up and sat unused for 10 years before being run? Do you know if the builder put storage lube in the bores? Did you add Diesel to the bores before running it? If not it's quite likely the rings have frozen in their grooves or the bores may have rusted over lightly ruining the honed pattern.

[Cooperman]

Might be best to whip the head off, measure the combustion chambers a d piston dish and distance down the bores to piston tops at TDC. Then do a C.R. calculation and, at the same time, inspect the bores.

[MIGLIACARS]

Might be best to whip the head off, measure the combustion chambers a d piston dish and distance down the bores to piston tops at TDC. Then do a C.R. calculation and, at the same time, inspect the bores.

nice advise again cooperman   a easy option

[Curley]

Ok so I think I worked out why my dry tests where so low.... Apparently I should have taken all the plugs out - lol

Did a wet test and got 160psi on #4, 120 #3, 140 #2 and 140 on #1. I've taken the head off and been quoted £200+VAT to chemically clean, reface, fit new unleaded seats, new valves, springs and a coat of paint. What do you think?

Also, BK450 or copper head gasket GEG300?

[Cooperman]

Check the bores to see if there is a 'step' where the top piston ring comes up to.

Also measure everything accurately and see what the CR is.

[KernowCooper]

If the valves were responsible for the low compression ? the wet compression test is still very low, are the valves showing signs of not sealing ? and BK450 is a very good gasket and used a lot on the 1275 series motors, and recommended

[Curley]

Check the bores to see if there is a 'step' where the top piston ring comes up to.

Also measure everything accurately and see what the CR is.

Will do Cooperman. There is a 'step' of about 2-3mm of black carbon type buildup at the very top of cylinder where the piston (or is it the ring?) doesn't quite reach the top of the deck. The bores all look good to me (limited frame of reference), there are no scratches or grooves and the faces are silky smooth. I also poured some petrol into each cylinders and waited 30 minutes and it was all still there. I assume these are all good things?

 

I was thinking I'd use a syringe of parafin, fill each of the cylinders at TDC and record their volumes? Should I also do this at BDC or can we just assume the stroke to be standard A-series 1275?

 

 

If the valves were responsible for the low compression ? the wet compression test is still very low, are the valves showing signs of not sealing ? and BK450 is a very good gasket and used a lot on the 1275 series motors, and recommended

 

Not sure I'd know what to look for? I know the head needs unleaded seats so I'm tempted just to book it in and get the work done.

 

The smaller of the two valves on 1&4 are a sort of greyish colour as are the plugs; the larger valves are black. 2&3 both valves are very black to the point that whatever the buildup is its cracked and crazed. 2,3&4 have a very heavy buildup around the chamber and valve faces - so bad you can pick it off. 

 

I've always been happy with the BK450 but my local Mini shop recon's I should use the copper. They say the copper ones allow for greater heat transfer between the block and the head. The BK ones create a thermal barrier and *apparently* this leads to the head getting hotter than it should. I understand the science but not sure if I buy it. Would it really make that much difference??

[KernowCooper]

I'd change Mini shops BK450 is the accepted gasket fot the big bore 1275 engines and IMO far better than the copper ones, does your local mini shop not realise there is water in the head and a water pump. there are members here who have used the coper gasket and had water sealing issues and changed for the BK450.

 

Maybe a thermal engineer here can say why but that statement to me about the thermal barrier sound like poppy Co*k to me .

Edited by KernowCooper, 29 October 2014 - 01:19 AM.

[MIGLIACARS]

your engine shouldnt be getting that hot,   I use the bk450 in my racer, 220hp at the fly

 

17 psi of boost so far so good.

 

 

keep with what you know

[jaydee]

I've always been happy with the BK450 but my local Mini shop recon's I should use the copper. They say the copper ones allow for greater heat transfer between the block and the head. The BK ones create a thermal barrier and *apparently* this leads to the head getting hotter than it should. I understand the science but not sure if I buy it. Would it really make that much difference??

 

 

Thats true only on ideal world, because copper is better at heat transfer. Thats not true on a real world application where the gasket wont be full copper.

There are two gaskets to use on performance A-series engines, the turbo gasket for engines up to 1310 (iirc) and the BK450 for any engine size.

Most reputable engine builders will confirm that.