NO OIL PRESSURE!!! Please help!!

[968ant]

Hello, I have a V8 Esprit, I changed the leaking oil cooler yesterday for a new item, everything went well but when we fired it up the oil light was on for about 30 seconds then went off, but the oil pressure gauge didnt move, also the engine sounded very "tappety" so I turned it off after about 3-4 mins with a view to seeking some advice, is this normal? Does it take a while for the oil pressure to build or is there something I should have done to stop air locks?

Any advice you can give will be greatly appreciated.

Thankyou in advance.

Anthony.

P.S. What oil pressure should this car run at normally??

[toyroom]

My oil pressure runs just under half way up the guage under load and just above the red line after ticking over for a minute. The factory say that this is normal. Think about it: The sump plug is the loweat part of the system so draining the oil should empty the oil cooling circuit. When refilling, you just pour new oil in the top of the engine. In other words, changing the oil coolers should be no different to changing the oil at a service. Is the guage on absolute zero or is it just very low ? The only other thing is that they recommend you put the new oil filter on the car full of oil. Did you do this. Still can't see it as a problem. If the oil light went out, the pressure should be OK. Is it possible that there is only the bare minimum of oil in the engine? How much did you put in ? Is it possible you have didturbed the oil pressure sender. Not sure where this is, by the way. I once has a similar problem with the temperature guage and a new sender cured it. Is your car 98 on or pre 98 by the way ?

[968ant]

Thanks for all that I really appreciate your help, nice to know I'm not alone!! I've got some time to do some more investigation tomorrow, I'll let you know how I get on.

Just as a matter of interest, mine is a pre 98 model, were there major changes at 98?

thanks again,

Anthony.

[toyroom]

Changes at '98 were mainly cosmetic, but... remember the Esprit is a hand built ongoing research platform so there were never more than a couple of hundred cars made to the same spec for any length of time !
Changes included:
Main one was change to small modern car style instrument binnacle with deleted boost guage.
Heater radiator valve was changed to electric motor operation rather than cable
Boot spoiler was moved to the boot lid from the car body (so you don't get a wet shirt going in the boot!)
Gear linkage was changed to a more direct mechanism.
Centre tunnel oddments tray was deleted.
Twin plate clutch came with V8 number 280 (mine is number 287) although conversion is easy.
new type of alarm
revised windscreen wiper mechanism
That's what I can think of!

[joeyo]

I would check the oil level to make sure you have enough oil in the sump/engine.

You said you replaced the oil cooler. Did you flush the new cooler out or at least inspect it first for internal debris? I have seen (a couple of times) that during the manufacturing/shipping of the cooler they sometimes get debris in them. Therefore MAYBE there is a blockage in the new oil cooler and oil is not flowing back to the engine. This is just a guess!

Also sometime in the V8 build life they changed the location of the oil pressure sending switch/unit. I think the early V8 had the oil pressure sending on the oil filter adaptor plate while the one on my 2001 is above the oil filter and actual on the engine block itself (which is a pain in the A*# to change if it leaks).

JoeyO
2001 V8

[gmherron]

I recently romoved both coolers and fittings when replacing my NSF corner (52V8). When I refilled the system (it had been draining for 3 weeks), it took 9 litres. I was amazed, as I expected 6.3 litres as stated in the service notes.

When I came to restart, I pulled the fuel pump relay, and cranked over (allowing time for starter to cool) to draw oil through the system.

Mine 'tapped' on one cylinder for about 10 mminutes and then just went quiet (assumed to be a sticking hydraulic valve tappet)

Glyn

Edited by gmherron on Saturday 3rd February 20:08

[MeLLoN Stu]

yep i'm going with what the man above says

pull the fuel pump fuse and crack it over until the oil pressure light goes out, and a few seconds after that. Replace the fuse, fire her up and let it run until warm. Not sure on the lifter assembly but if they are hydraulic they're probably just taking their time to run. Maybe something to consider changing when the oppertunity arises.

if you've ran it for 3 or 4 minutes with genuinely zero oil pressure i'd be getting a little on the nervous side, big end bearings especially dislike oil starvation lol. Could just be a little air in trapped in the system around the oil pressure sender / sensor, or a failure of the sensor itself, if your engine isn't rattling like a champion, which i'd expect it to be with 3 or 4 minutes of no oil pressure. Not tappety type rattles, the type that get your wallet shivering.

Just do the usual checks, oil levels according to how they say to do it in the manual (not sure if they state warm or cold oil). Even if you've only got 50% oil in the system i'd expect it to hit a fair pressure if the oil pumps are half decent, enough to kill the oil pressure light anyway. So i'd be looking at something related to the sender / sensor right off the bat if you're half sure you've got the right oil level right and have cranked it over without the fuel pump fuse in.

Edited by MeLLoN Stu on Tuesday 13th February 07:14

[968ant]

thanks for the advice, I've not actually not had time to fire it up again yet but I'm hoping to sometime this week, I've now got a workshop manual where it says to "purge" the system? I'm assuming this is to prevent air locks? although I wouldn't have thought that this would be a problem?

thanks again,

Anthony.

[f1karting]

My 0.02

On the 4pot the OP guage feed line is a mile long and takes a while to develop pressure.

If concerned, I would go buy an oil/fuel rated pressure guage and appropriate fittings and thread it directly into the oil guage take off port and read the pressure directly from the oil gallery.

I had similar trouble on a lotus TC engine on a fresh start up.. it scared me to death looking at zero pressure.. putting trust in my assembly lube, I let her idle for what seemed eternity (about 15 secs) and finally 'pop' full OP. The feed line on that OP guage was about 1m.

J

[968ant]

Hurray!!! weve sorted it, turns out that there was a smaller fitting on the oil cooler we had fitted? we've fitted a new one and all is well, oil pressure is where it should be a couple of seconds after start up.

thanks for all your advice,

Ant.