Help! No oil pressure!

[david.g.chapman]

Driving home from work today in my twin cam +2 I noticed the oil pressure was lower than usual, but still just about OK.

I re-started the engine after an hour and found no pressure at all!

Stopped the engine quickly, took the sender unit out, restarted again - no oil coming out of the sender hole! Stopped engine again

I can't take the oil pump out of the engine easily, so I took off the rotor housing cover to check if the pump was turning - OK. Replaced the O ring which looked a bit flat, and refitted the cover. I then removed the oil filter and turned the engine over on the starter to see if the pump was sucking anything up (yes, there was oil in the sump!) - nothing came out.

I then suspected the oil pickup tube in the sump. I took the sump off. The tube looks fine - nice and tight in the block. I can't see any blockages at the moment, but will probe the oil pickup tube. I am not optimistic, as the mesh filter cage on the tube base looks OK.

Any ideas would be appreciated.

Dave Chapman

[david.g.chapman]

I have taken out the oil pump. On my car with a standard lotus chassis I can just drop one side of the engine 10mm and out she comes.

I have probed every oilway up to the sender opening and there is no blockage.

I can find nothing wrong with the pump. All clearences are in spec, and the insides are clean. Is there any testing I can do with the pump out of the car?

Dave Chapman

[types26/36]

David,
There are measurments you can make and are in the workshop manual in Tech Data but in my opinion it is not worth the effort as the pumps are not that expensive and you already have it off.
At least you will know a new pump will be O.K. although I relise you are trying to find a definite answer why you lost oil pressure.
If you do fit another pump just remember to prime it well.
Brian

[john.p.clegg]

Just a guess,but,if your oil pump is worn (knackered) it will not pull any oil up from the sump and hey presto the symptoms you suggest.
Ford pumps are easy to come by and a change can be done as said earlier just by lowering the right hand engine mount....
John

[david.g.chapman]

It's fixed!

The cause (I think) was subtle and fooled me first of all. When the sump was in place, the gauze filter that protects the oil take up pipe was actually blocking it. There is a disc of metal on the bottom of the filter, and some old RTV has lodged between the disc and the gauze. With the sump in place there was virtually no clearance for the base of the pipe above the floor of the sump. and the pump suction had completed the seal between the disc, the pipe and the RTV!

I think the pipe is set too low, but it is firmly fixed in the block. I have flexed the gauze filter so that the disc cannot cover the pipe. The disc still acts as a rubbing shield on the sump, however, to protect the gauze.

I re-assembled, and all is well.

If you have the sump off for any reason, it is worth checking this point.

Thanks for your replies,

Dave Chapman.

[rodgerslotus]

Oil Pressure Problem,

I will attempt to be brief.

I purchased a 72 Elan +2 with 21K orginal miles. It had been sitting for the last 27 years in a enclosed dry garage. Body and interior in great shape, plus it had always been in a Southern climate.

I was successful in getting the engine to crank (50 psi oil/ 150 psi piston pressure) and run poorly, so I started the normal repairs to get the car on the road, carb rebuild, brake and clutch hydros. I flushed the oil and coolant systems at least 3 times.

After 24 miles of driving over a 2 week period, not over 40 mph, I noticed the oil pressure dropping out to 15 psi after coming up to normal temp. I returned home and put in back in the garage. Next morning I started the car and only got 15 psi on the oil pressure. I suspected the oil gauge and used a spare Morgan oil gauge. Results were 20 psi.

Purchased a new oil pump from Bean ( 60 psi ) and started removing the old pump and now realize I need to drop the engine 10 mm after reading Mr. Chapman oil pressure problems which are similar to mine. I have not removed the oil pan to inspect the sump for blockage ( Good Idea ).

One question, prime the oil pump? What method and how? Some one please advise.

Are there any other words of wisdom or advice out there before I proceed.

Regards,
Ty Rodgers - Tiger, Healey, Morgan, Low Oil Pressure Lotus

[types26/36]

Oil Pressure Problem,
I suspected the oil gauge and used a spare Morgan oil gauge. Results were 20 psi.

One question, prime the oil pump? What method and how? Some one please advise.

Before pulling car apart, do you have an electrical or mechanical oil gauge? if electrical I suggest you verify the readings with a mechanical gauge, voltage stabilizer can give problems with electrical gauges.
The way I prime the pump:
fill oil filter with oil (could take some time if it has the check valve)
fit oil filter to pump
turn pump by hand feeding oil into pump untill air is expelled
remove filter (cant fit pump with filter on).....makes a mess!
fit pump
fit oil filter
loosen end cover on pump, tilt slightly and inject oil behind cover with oil can
quickly refit end cover
Turn over engine with no plugs in and hope there is oil pressues
If no oil pressure, start engine and allow to idle a miniute or two.
All being well clean up the mess!
Brian

[david.g.chapman]

When I re-assembled the oil pump, I just added a few drops of oil to the rotor, but did not prime the pump by filling it with oil.

The pump should still suck up the oil (well it did with me anyway), but you are running the engine that much longer with no pressure. With me, it took about 6 seconds at 2000rpm to pressurise the gauge sender from when the engine fired. My pump clearances were within spec.

Dave Chapman

[Hamish Coutts]

Just did the same job last night on my +2 S130. Picked up a new pump from QED at their stand at the Silverstone Classic last weekend (and what a fab weekend that was - premadonna F1? eat your heart out!!! This was real racing).
Found I had to drop the engine about 3ins to get the pump out past the steering column.
I filled the new filter with oil over a period of about 15 mins (to let the oil soak into the filter) and primed the pump.
Fitted the pump sans filter, tightened it up, then fitted the filter. Turned the engine over on the starter with plugs removed and got oil pressure after about 3 secs.
The whole thing only took about an 1? hrs (including removing and refitting the carbs).

Regards,

Hamish.

[types26/36]

The whole thing only took about an 1? hrs (including removing and refitting the carbs).
Hamish.

WOW! Your spanners must have been red hot!
Brian

[Hamish Coutts]

It's amazing what you can do when your motivated. I was going to help a chum with his +2 and had to use mine to get there! (he was also giving me a case of wine)

Regards,

Hamish.

[types26/36]

had to use mine to get there! (he was also giving me a case of wine).

.........and I'll bet your car went well on the way back
Brian

[Hamish Coutts]

Brian,

The car wen't like a wee rocket . Well, as near a wee rocket as possible when the engine is running in!

Regards,

Hamish.