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no oil pressure. fresh rebuild.


MightyJoe

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i've finally got around to getting my cortina started, everything is new. bearings, high pressure oil pump, cam, lifters, pistons, everything. got it fired up pretty easily and wanted to hold it at 2000 rpm to run the cam in but the oil pressure light wont go out. i've had 2 different senders in the hole, and tested them manually with a scribe pushed in the switch ( which made the light go out) . i left it out the hole and some oil does come out but it doesnt come out with as much force as i would've expected. 

i've turned the engine over a few times with the plugs out (for speed)  and the light still wont go out. i dont want to keep doing this as theres a chance i'll fuck the cam at the least, and at the most the whole engine. anyone had any experience with this? i took the pump off the check its not siezed and its all good, everything was primed before anyway. 

i'm using lucas run in high zinc oil SAE 30. 

its been run for about a minute maximum so far and im shit scared to even turn it over now, i cant afford to fuck this up and rebuild it again. i'm thinking i have to drop the sump and check the pickup pipe. i did this when first assembling but you can never be too sure. 

its a 1500 pre crossflow kent engine. 

 

 

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no even checked in the manual earlier. theres only 4. 2 to alternator, 1 to temp sender and 1 to oil pressure.  the oil pressure is a spade connector and the water temp is a bullet. as well as the colour difference

 also i checked the switch manually earlier. earthed it to the battery and pushed a small scribe to activate it and it worked as it should. 

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You're right to not put any load on the engine as someone has made an error and you could be in deep trouble if you get load on it without adequate oil pressure. I assume it's a 120E block

Underneath the RHS engine mount will be a tiny grub screw which is directly connected to the oil gallery. I assume you didn't do anything with/to that? If you get desperate you can remove it to see if there's oil pressure there, but that's a shitty job so leave that to a last resort.

Additionally, the cam bearings need to be rotated correctly to allow oil delivery, and the front spacer (if there are any) under the rocker shaft post needs a hole in it too. 

There's very little oil delivery to the rocker gear so unfortunately watching the valve gear isn't hugely indicative of oil delivery. 

It depends on how much of a rebuild you did, but one guess is that you have a gasket on backwards, or a faulty gasket. Perhaps start with the oil pump gasket... but you also need to consider the head gasket. The worst case is that you installed the main or big end bearings incorrectly, in which case it's sump off (at best).

DO NOT PUT LOAD ON THE MOTOR. It may not be too late to save this

There's a 120E oil flow diagram somewhere. I may have seen it in a Hanyes manual. Have a look on Google and then you'll have a better idea.

Good luck mate

 

 

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55 minutes ago, MightyJoe said:

 also i checked the switch manually earlier. earthed it to the battery and pushed a small scribe to activate it and it worked as it should. 

IIRC the oil pressure light goes OFF when the circuit is earthed. I assume that's what you did to test it from your description, but I thought I'd mention it anyway

 

EDIT: I read your first post properly and now understand what you've replaced. Assuming the BE and main bearings are the correct size, then the most likely problem is that you've put one of them in wrong. I'm getting old and my memory is bad, but I'm almost certain the oil circuit basically starts with the crankshaft on the 120E, so perhaps that's what's happened. If I can think of anything else I'll holla...

 

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thanks for that info. 

Yeah its a 120 block. 6015 casting number. not an L block but its a 1967 mk2 with the mk1 running gear so shes a bit of an oddball. The engine was completely stripped to the last grub screw, everything was washed, acid tanked and assessed and replaced as necessary. the only original parts are the cast block, head and crank. everything else is brand new.  i paid the engineering company to assemble the short block but i installed the pickup pipes and sump and oil pump etc. i bought big end bearings and cam bearings on their specifications. it was also line bored to accept square main caps so i would assume the tolerances would be perfect.  i've checked and rechecked the oil pump mounting and i took it apart earlier and had a good look over it and as far as i can tell the oil pump is ok. i did replace the grub screw behind the engine mount at the time as well as the front and rear oil gallery ones behind the timing case. i took out the oil pressure switch earlier and turned it over a few times and oil did come out but it wasn't as much as i would've thought and yes, i understand what you say about the oil pressure switch but i have 2 of them and both are behaving the same, one off the original engine and one out of the box new. i think i'm going to have to drop the sump, check the pickup and return pipes are still seated properly and go from there. i honestly dont know what else to do though if it isn't that. 

i hope to hell  i havent done any serious damage. i can deal with a flat cam but cant afford to rebuild the motor again :(

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If you've fitted square main caps I assume they're off a crossflow block. Bloody good idea if you're going to pull high revs.

You got it line bored? Jesus man. That's awesome. If they sized it all correctly and know what they're doing then the main bearing tolerances should be OK, so it's probably wise to look for an assembly error... and it may not be your error - but theirs.

6015 block: Does it have a 6 bolt crank then? They have a fraction more stroke than the earlier 120E IIRC, but one thing to watch out for is the pilot bearing (to the gearbox) as I think they're a bit different... but that has nothing to do with oil pressure so I'll shut up now.

If you haven't put load on the motor (i.e. tried to drive it) then you are unlikely to have done much harm yet. I wish I could remember more but I can't think of anything except a rotated bearing (that's blanking off an oil gallery). I guess it's possible that you fitted grub screws that are too long, but it's probably worth thinking hard about your next move first. If it was me I think I'd pull the motor out and get it onto an engine stand, but perhaps there's another diagnostic step that I haven't thought of yet. 

Sorry, that's probably little help, but I wish you the best sir. Line bored! OMG. Are you my adopted son? So awesome

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no i bought aftermarket ones, i couldn't find any crossflow ones and they would've needed machining to fit anyway. yeah i want to be able to use the cam so though i'd be pulling some silly revs. until the gearbox shits itself. anyway. its a 5 bolt crank .

 The machine shop came on a recommendation and weren't cheap but they do heaps of racecars and he knows his crossflows from the race circuits so i am confident in his work. i am going to drop the sump as soon as i can bear to look at it again and go from there i think. no load on the motor, it started pretty much off the bat and i held the revs for maybe 20 seconds,  no pressure so i turned it off, checked a few things, started it again for another 20 seconds, turned it off and have turned it over with no plugs in a couple of times. i used heaps of assembly lube and oiled all the bores etc well before i attempted to start it. 

i really cant be arsed to pull the motor again. really! but man. i should've just stuck a ca18 det in it and be done with the fucking thing. 

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Has the oil gallery core plug been installed in the back of the block? I would take out the spark plugs and hook up an oil pressure gauge, then crank the engine over and it should show oil pressure. Failing that I'd say it's in the oil pick up pipe or your engine builder has stuffed up the main/big end bearing clearances. If you have had it line bored check you have used the correct main bearing shell size. Engine builder should have checked clearances any way. 

 

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This is a tiny Welch plug?  If so then yes I did that myself. I also installed the grub scewws each end of the gallery. There is no oil escaping anywhere. I think I need to find a manual oil pressure gauge and hook it up. I would hope they checked everything tbh as I've never assembled a bottom end before I wanted it to be right hence why I got them to assemble the short block.  Oil pick up pipe is my only logical step I think. If there's nothing obviously wrong there I'll have to take the engine out and strip it back down I think. 

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So leave the pump on and just pump oil through the filter pipe? I was thinking it could be airlock and thats partly why I started it the second time and held the revs up a bit but they're not exactly sealed, they vent to atmosphere and the rocket cover was off too. ill try that though cheers. 

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