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I swapped the old x20xev for a replacement one, with less miles, fitted it in, cranked it over (ignition system switched off) and took AGES to build oil pressure, but It did eventually. Started it, sounded fine, but switched off as it was getting late, and it only have the exhaust manifold on.

Next day wanted to run it for longer. Cranked it, oil pressure wasn't building quick

I figured the pick up pipe may be blocked, so managed to get hold of a shortened sump, with new short pick up pipe. The old one wasn't blocked, and the new one was perfectly clean, fitted it all, new seals, still not building oil pressure enough to getnthe light off

I've tried several pressure switches, sump swapped, pick up swapped, but to clarify, it does appear to make pressure eventually, but just took about half an hour, including several battery charges to get there


The relief valve moves fine, and isn't worn, scored, or anything. Spring looks good, and it the steel piston comes out smoothly.

Next step, new oil pump. But what else could the problem be?
Oil pump broken up? Blockage somewhere else? I don't really want to strip the whole thing, but can't think what else to look that could be the problem

Thanks for any guidance!
 

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I guess if you have checked there are no blockages, no badly worn shells or bearings letting oil pressure out internally, and the pressure relief valve isn't sticking, it does really only point to needing a new pump.
 

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Discussion Starter #4
I guess if you have checked there are no blockages, no badly worn shells or bearings letting oil pressure out internally, and the pressure relief valve isn't sticking, it does really only point to needing a new pump.
Thanks for the message! There's not really much of the pump left, after changing the pick up, that could be blocked. Any blockage after the pressure switch would still show pressure. When I took the old sump off, the remains of the last oil was black so not recently changed, and not too bad, the strainer was ok. And no obvious evidence of metal in the old sump. The new short one came off a c20xe national hot rod race engine. The remains of the oil was like grey metallic paint, so I'm happy the bearings and shells are ok. No movement when I tried moving by hand. Not sure if that's then right way to check. I usually avoid doing anything with engines, but know I need to start! I built the rest of the car

What way can the pump fail? Worn gears? Something else breaking up? Is there anywhere I can blow compressed air in to dislodge any blockage?
I've got one in order, when it turns opup, I'll decide from there whether I'll do it, or just send it in to a garage to do the pump, fit the LSD, and run it on the dyno
 

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Discussion Starter #5
Would make total sense to whip the pressure valve back out, and make sure (although it comes out fine) there's no gunk at the top keeping it open
 

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heard quite a few people having a similar issue, right after a rebuild, or after a brand new pump is fitted.

sometimes in these instances, when there empty/dry, they can get air locked, and need priming.
you could try pouring oil into the relief valve hole, and into the pressure switch hole, as well as filling the oil filter up as well, it all helps.

ive heard of some people having to pack the pumps full of vaseline, to help them seal some pressure.

if you can get as much oil into it, as you can, from any or all holes, and spin the engine over lots, with the spark plugs taken out. it might be enough, to blow some oil through it, and push any air out, that might be in there.

worth trying, before you pull it all apart, and fit a new pump.
 

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but but but, what oil you using, may be try a little thicker oil as you are not driving it in minus -35C so you don't need that fully synthetic 0W40 or whatever thinnest oils you get, I would use SAE 20/50 or even thicker, as it would build oil presure much more quicker
 

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I swapped the old x20xev for a replacement one, with less miles, fitted it in, cranked it over (ignition system switched off) and took AGES to build oil pressure, but It did eventually. Started it, sounded fine, but switched off as it was getting late, and it only have the exhaust manifold on.

Next day wanted to run it for longer. Cranked it, oil pressure wasn't building quick

I figured the pick up pipe may be blocked, so managed to get hold of a shortened sump, with new short pick up pipe. The old one wasn't blocked, and the new one was perfectly clean, fitted it all, new seals, still not building oil pressure enough to getnthe light off

I've tried several pressure switches, sump swapped, pick up swapped, but to clarify, it does appear to make pressure eventually, but just took about half an hour, including several battery charges to get there


The relief valve moves fine, and isn't worn, scored, or anything. Spring looks good, and it the steel piston comes out smoothly.

Next step, new oil pump. But what else could the problem be?
Oil pump broken up? Blockage somewhere else? I don't really want to strip the whole thing, but can't think what else to look that could be the problem

Thanks for any guidance!

After a half hour of cranking there, let alone all the other times, it's time to drop the sump and check just how badly the bearings have been damaged - you may also be looking at a crank grind...
I would expect the oil pump to also be destroyed, as heavy wear's the most common reason for the poor vacuum that's required to draw the oil into the pump gears and then pressurise the oil.
When you get the engine back from being rebuilt, you should be looking at an almost immediate pressure build up not more than 5 seconds with spark plugs out - if it takes more than 10 seconds, even after prolonged sitting, you have a problem - DO NOT continue cranking until you know EXACTLY what the problem is, and if it's OK to continue!

Tip - if I have had an engine sitting for a while, I remove the oil filter and backfeed the oil pump using a hose and squeeze bottle of engine oil - bit messy, but gets the pump primed. If the engine was rebuilt and not run - or as good practice, anyway, fill the filter before fitting also.
If the engine is on a stand, rotate it so it is upside down, and with the filter removed you can prime the oil passages, and pump, quite easily with some oil - don't overdo it, though, as it will eventually find it's way out the breather(s).
 
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