14 replies to this topic

[minijack67]

Hi everyone. Some much needed assistance please.

 

Please bear with me. Bit of a odd one maybe?

Changed blown head gasket, did oil and filter change at the same time. Cranked over with no spark - no oil pressure. Orange light on and oil gauge reading nothing. After a bit of thought, removed head to check head gasket did have clear oil holes (you never know). All ok there. I thought maybe air in oil feed somewhere. (We were towed home, up and down some steep hills, so though oil might have left pump. Re-primed pump, loosened oil filter, turned over engine to make sure oil was moving. Oil light went out and pressure up to 70lb. Oil coming out of gallery on block. All reassembled - turned over without spark and no oil pressure again. So, same process and oil pressure back. Tried a few more times, all was ok, so fired it up. Ran for about 20 mins at 65/70lb no fluctuations. Left for 2 hrs and spun over again (with no spark). No pressure again. Took turning it over for about 20 secs to register pressure. Went back after another few hours and no oil pressure at all. At this point car put back in garage!!!!

Oil pressure has never been an issue before. Engine only done 3k miles. What's everyone's thoughts please. All ideas are welcome. Thank you

 

Edited by minijack67, 25 April 2016 - 09:25 AM.

[Dusky]

Usually a problem at the oil pump gasket.

[sledgehammer]

I wonder if something has got under the relief valve seat - or the seat is sticking , allowing air into the oil pump area / drain down ?

 

worth a look

 

give it a polish up & check the spring condition

Edited by sledgehammer, 25 April 2016 - 09:33 AM.

[minijack67]

Thanks for your replies.

 

I've checked the relief valve and all seems ok.

 

I was hoping nothing to do with oil pump, to be honest!! It was fine before i had to do any of the work. Oil pressure has always been consistent.

 

Could the oil pump gasket just fail like this? Are there no tell tale signs beforehand? 

[sledgehammer]

change oil filter - costs a few quid & eliminates another item (as it was the only thing changed , other than head gasket), before getting more serious

 

I can't see how it could cause the problem , but stranger things have happened 

 

& there are some crap oil filters out there

 

Unipart are the best IMHO - never had a problem with them

[nicklouse]

I have to ask why are you turning it over with the ignition off (no spark) it will be turning over slower than when you did not see a problem.

 

How is it when you just try starting it?

 

oil pressure is a result of two things. a pump and resistance in the bearings.

 

a poor flowing or a good flowing oil filter will not really effect the oil pressure. changing the head gasket should have no effect on the pressure as there is no real pressure up there.

 

I feel you are seeing a problem that is not really there or you will need to pull the engine as the pump gasket could be failing. (but that would also show no-low pressure when running).

[minijack67]

Thanks for your replies.

 

I remove the spark plugs when turning it over. I have always done this whenever changing the oil/filter, as i like to make sure the oil is pumped around the engine before starting up.

 

The oil light and oil pressure gauge normally register within 20 seconds or so, after a oil change. After this, the oil light and gauge register with a couple of seconds.

 

I agree that the head gasket will have no effect, i'm guessing co-incidental. I just listed the work i had carried out.

 

I have re-primed the oil pump and replaced the oil filter again and checked the oil pressure relief valve.

 

When i did finally get oil pressure a few times by cranking over with no plugs, i then started it up. The car starts on the button and pressure was at 70lbs. I left it running for 20/30 mins to

put a heat cycle through the replaced head gasket. I was able to stop and start the car a few times and oil pressure was constant.

 

It was only when i went back to it a couple of hours later to be sure i still had pressure that i again made the decision to spin the car over with the plugs removed. The oil pressure had again disappeared.

After about 20 secs, the orange light would go out and oil pressure would climb. If i then did this again, straight away, it took another 20 secs for the pressure to increase. 

 

As the car starts on the button, i'm not prepared to start it unless i know oil pressure is present. I'm not overly convinced that its the oil pump/gasket, but struggling to find any answers.

 

Is it possible that i have/am getting a air lock or similar?

 

Thank you for your replies so far. 

[Rob Gavin]

do you know which pump is fitted?

[nicklouse]

 

Is it possible that i have/am getting a air lock or similar?

 

 

not really as there is nothing there.

 

you have not changed anything else on the oil side other than the filter?

 

what oil?

[sledgehammer]

how smooth was the relief plunger in the bore ?

 

if it isn't seating properly , it can let air into the pump allowing drain down when engine stopped

 

clutching at straws now

[minijack67]

Thanks for all the replies.

 

Not sure on the oil pump. Minispares i think. Never had any issues at all, before now.  

 

Apart from the head gasket, i only drained the oil and replaced with Halfords Classic Car 20/50.

 

Oil filter changed twice.

 

It was smooth inside the bore , but I have ordered another relief valve anyway - 1 with the ball and spring, the other with cup and spring. I haven't decided which to use yet, due to so much difference on opinions.

 

Clutching at straws is what i've been doing, but it's got to be worth trying. A simple fix if it works.

[nicklouse]

not the best oil for the Mini so I have read.

 

what oil pressure gauge is it? mechanical or electric?

[minijack67]

I've always used this oil and change it about every 500/1000 miles. Its not my everyday car, so mileage is pretty low.

 

Oil pressure gauge is mechanical and i have also change the oil pressure switch. I know they work in tandem, but like i said earlier, running out of ideas.

[nicklouse]

so these are new?

 

or were there before when there was no issue?

 

if there before could you have knocked the electric sender?  if new fit the old sender.

 

or blank the electric sender of (remove and just fit the mech guage) the sender body may have a leak letting air in.

[minijack67]

They were there before and never had an issue.

 

I changed the sender because i had a spare new one. Although like i say, both gauges work in line with each other.

 

I didn't expect any difference really, but you never know!! Anyway, there wasn't so i put the old sender back.

 

Good point about blanking the electric sender off. I have a T piece in the block so i can run the oil line. I haven't checked that for any possible leak.

 

I did pull the electric sender, turn the engine over to see if there was any oil coming out at that point, which there was.