39 replies to this topic

[2009poolesparky]

was driving home on the motorway the other night. temp guage went very hot (120+) pulled over to have a look under bonet and everything was covered in oil (the whole lot out of the engine) mamaned to get a tow home coming to inspect it tonight, im thinking it could be rocker cover gasket? i think there is quite a high crank case pressure any ideas? thanks alex

[KernowCooper]

wash it all down and restart and see if you can locate it, have you noticed ant leaks there before? when it ran hot was it still on 4 cylinders?

[2009poolesparky]

Ok so have done that, it's coming out of the dipstick! And ideas? It's not a tight fit dipstick but I didn't think they were meant to be anyway

[Cooper93]

i had this issue, the rubber perished on the dipstick itself,, bought a polished one from minisport,,, problem solved :) they came with a double rubber so a better seal

[KernowCooper]

Dipsticks have a small rubber seat there not a tight fit, if you remove the filler cap whats the crankcase pressure like ? is it running ok ?

[2009poolesparky]

ill have to check again of the rocker cover, the engine has had a rebuild about 18k miles ago, both brathers seem fine, ive replaced the rocker cover gasket. MiniMad do you know the part number for the dipstick you bought? or a link? the oil only seems to come out when in gear and driving as opposed to just revving it up in neutral

 

got it up on the ramps last night and had a look underneath, oil had dripped down and been blown back underneath so gave it all a good clean

[tiger99]

It is very surprising that so much oil has come out of the dipstick hole. You really do need to check for pressure in the rocker cover, at the filler cap, before doing anything else. If there is excess pressure there, which most likely means a head gasket, or failing piston, or at least piston rings, a new dipstick is not going to help. Now a failing piston would possibly be as a result of teh overheating, and may be caused by timing too advanced, or too much compression causing pinking, or even a weak mixture, as well as possible cooling system faults such as failing water pump or muck in the radiator.

 

It is important to go about diagnosing this logically. Check that the oil level is correct, add as needed, and the water level is also correct. Is there oil in the water, or water in the oil? (A gasket leak between oil and combustion spaces does not necessarily involve oil or water, but a gasket weeping over a large area due to teh head being warped or not torqued correctly certainly will.) Run the engine and check for crankcase pressure. If there is any (there should normally be some slight suction, but it will be pulsating), then the next thing to do is to have the head off and look for a blown gasket. If the gasket is ok, look for scored cylinder bores or any visible piston damage. Hopefully it is only the gasket, because going any further involves a full stripdown.

[Yoda]

Compression test before removing the head may save time and money!

 

You Missed that one Tiger99 LOL

 

It may not be too surprising regarding the amount of oil lost from the diptick hole if it was a while ago that the oil level was last checked! 

[tiger99]

I did indeed miss the compression test, because I personally would whip the head off for a look, as I can do it quickly, and I have never actually needed a compression tester, so don't have one. But it is a reasonable thing to try, although any low pressure readings may simply be valve wear, easily fixed. It doesn't tell the whole story.

 

I do have a Colourtune plug, which is very useful to set up the mixture, and of course a timing light and dwell meter, because they are needed regularly with any classic car. But the few gasket failures I had on Minis were rather easy to diagnose without any instruments, and the only engine that wore out its bores was again obvious by the exhaust smoke, although it did not eject much oil through the dipstick hole.

 

But if I had an endoscope or camera I would have a look through the plug holes first. It is something that I will get because it has other uses too, like finding wiring, pipes and lost tools under floors during house renovation. That also does not tell the whole story, but in my opinion is a more useful instrument as you can also use it to monitor the condition of sills and other box sections regularly. Properly built engines don't need as much monitoring of their internal condition.

[2009poolesparky]

the fuel is spot on and the engine has had a total rebuild about 18k miles ago and hasnt really been used for the past 6 months, theres no oil in the water. what should i be getting at a compression check? its a 1991 1275cc engine

[Yoda]

As long as its over around 120psi and within about 5% the same per cylinder we can probably rule out rings/bores. Obviously i would like to see higher compression readings, but we are looking for the reason for chucking oil out, not running issues at the moment. Plus i would expect smoke from the exhaust if the rings/bores were really bad. 

 

I must admit though, if it seems to do it under load only, it may be difficult to find a problem with the car static.

 

If i were you, i would get the compression test done, make sure there is no excessive smoke from the exhaust and if that looks OK, i would get a new dipstick and see how you get on.

 

Too much diagnostic advice can be worrying for no real reason.

[2009poolesparky]

ok well ill have to find somewhere /someone with a compression tester, i did manage to put the car on the 4 poster ramp and jack up the front wheels, but even in gear like this there is no load on the engine, when i had it like this i pulled the dipstick out a bit and the oil was gushing out, i guess when driving on the motorway the pressure builds up and pops the dip stick up, there was oil everywhere in the engine bay when it happened even on the bonnet and bulkhead, it pumped everything out!!

the exhaust doesnt smoke one bit so dont think it could be rings...

[albo]

hi just a thought,, does it have a high pressure oil pump fitted,and maybe a stuck relieve valve

[minimadles]

just a thought check out the breather system for blockage

[2009poolesparky]

im not sure if it has a high pressure pump, ill see if i can find the history that might suggest it, i was going to take the breathers off and clean them through to be certain, is there a mesh inside them? what would be the best way to clean them? submerge in petrol??

 

alex