No Oil Pressure

[Kendo]

For the oil pressure gauge, does oil have to fill the pipe, or does the gauge measure OK with air in the last bit? If it has to be all oil, how do you purge the air?

[4129R]

Maybe an oil gallery pipe plug was left out.

That thought had crossed my mind, but where would that plug be on the block?

I have 2 other engines out of cars, so if I had a clue where to look for those plugs on those ones, I would know where to start looking on the engine in the car.

[EuropaTC]

How long would you run the engine for with no recordable pressure, just to see if the pressure builds up as the engine fires at say 2000 rpm? What am I missing here?

Personally I wouldn't run it at all but the 10 seconds you mentioned sounds ok with no real load.  If it jumps straight to idle at 1500-2000 then it should be at least at 40psi, mine hits half way on the dial once it fires.

As you say, pressure should build on cranking, or at least it does on mine if the filter is primed full with oil after an oil change. The Elan will show 20psi before it fires up, I'd expect a few seconds of turning over to do something similar with yours ?

Brian

[jbcollier]

I had the sump off my Seven's crossflow all winter.  When I put it all back together, I had a heck of a time getting oil pressure.  I cranked it a lot.  That included a new pump, packed with vasoline, etc.  What I eventually did was get a large syringe and force oil backwards through the pump via the oil filter mount.  I also forced oil into the engine through the centre.  Got oil pressure then.

[4129R]

My first plan is to run the engine 3 times for less than 10 seconds, with a long gap in between, to see if I can get any oil pressure.

My next plans are to check the oil pressure gauge with compressed air to see if it is working, and then to trace the oilways on another engine to see whether a grub screw is missing that is allowing the oil to go back into the sump rather than to be forced through the crank oilways, and up to the cylinder head to feed the cams.

The oil will take the least path of resistance, and if an oilway is open, there will be no back pressure, so the oil pump will show no pressure at the gauge take off union on the block.

[Pfreen]

I think there is a plug behind the front cover.  However, I assume your engine hasn't been just rebuilt, so it has probably run before in its current configuration.  I have also had issues with the newer oil pumps like JB,.  I ran it for a short amount of time less than 15 seconds at idle to get oil pressure, but I had put everything together with assembly lube. 

[kram350kram]

I know little of the internal design of a twin-cam but is there not a way to rotate the oil pump externally with an electric drill or by hand?  I prelube all motors with a hand drill prior to start up.

[jbcollier]

Not on a Lotus/Ford TC/crossflow.  The oil pump is gear driven off the jack shaft/camshaft.

[EuropaTC]

Possibly a dumb question in light of you having tried two pumps but is it worth removing the plate and checking the side & face clearances on the lobes to see if they are within spec ? 

I know new pumps should be perfect but maybe there's some manufacturing tolerances that are going adrift depending on how/where the parts are made, it wouldn't be the first time we've had new kit that doesn't meet older specs.

Brian

[4129R]

Possibly a dumb question in light of you having tried two pumps but is it worth removing the plate and checking the side & face clearances on the lobes to see if they are within spec ? 
Brian

What am I measuring? The pumps are Ford manufactured.

[Richard48Y]

Hmmm, how about temporarily replace the oil filter with a remote filter adapter and external pump to circulate oil through the non-running engine until all air is expelled?
Might make a difference?
And should show oil pressure at the gauge port unless that is blocked in some way.
If oil pressure can be obtained with the external pump that should provide a few clues.

[EuropaTC]

What am I measuring? The pumps are Ford manufactured.

It's certainly in the straw clutching category but given how there are tales of trunnions not fitting, ignition parts not working, etc, I thought it worth a look as there seems to be a real problem in getting this pump shoving oil about. I've only ever fitted 2 pumps and both have been fine, even the old ones haven't been bad but as this is proving troublesome.....

Brian
Edit to add, just realised there's no dimensions. I'll go and find them....

[4129R]

Today, I tested the oil pressure gauge by squirting compressed air into the small hole, and it worked perfectly.

I cranked the engine with the spark plugs out 4 times for 10 seconds, not any movement of the needle on the gauge.

I started the engine for 3 seconds, 4 times, it revved at 2000 rpm, and no movement of the needle of the gauge.

I am now about to investigate the oilway from the pump to the oil pressure take off on a spare engine I have lying around, to see whether there is a grub screw covering the oilway behind the front plate close to the jackshaft locking plate.

I fear I will have to take the engine out and pull it apart to check every oilway is clear and closed off.  I have run out of ideas.

I will check the tolerances on the oil pumps, but I cannot see how they can wear if they are totally surrounded by oil all the time.

[Pfreen]

I don't think the new pumps you buy are made by Ford.  The Lotus Elan site may have more info.
You do have a mystery for sure.

[4129R]

Oil pump tolerances checked, and they are 2 thou, so well within limits.

Oilway checked on spare engine. It goes from the pump to the oil pressure take off point and is capped by an allen headed grub screw where the lay shaft plate holds the layshaft in place, just behind the chain sprocket.

Next task, see if I can see that part of the engine from the top with the cam cover removed to see if oil is leaking out of that oilway.

Local garage says the oil has to be going somewhere if it is not pressurising the pressure gauge take off.