no oil pressure. help please

fiveoho · Dec 18, 2009

i know its a mod motor but im confident some of you guys can give me some direction

decided about 15 min ago i would start my car, after sitting in the garage for a week. started right up but idled very rough for 2-3 seconds then adjusted and smoothed out. i looked down at my gauge and no oil pressure. i quickly cut the car off. the gauge itself i believe is working because with the car off, the needle was bottomed out, with the car on the needle was under the red mark.

its a 2000 gt with 87,000 miles and no mods other than a programmer. had it about 3 weeks and the oil pressure has been just fine ever drive its been on. needle is right in the middle.

could this be the oil pump? if so, isnt it odd to take a dump at 87k?

could it be the oil sending unit? this just controls my gauge, correct? if that be the case, then i actually have oil pressure - correct? but why would the needle move if the sending unit is out?

car ran a total of about 7 seconds. i noticed no motor noise and ticking. did i hurt anything?

other ideas??

Pokageek · Dec 18, 2009

I know this isnt a stang ..but I had a friend with a miata that showed LOW oil pressure when it was perfectly fine. He had it tested at the dealership and its just the gauge that always read a little low.

Adam95GT · Dec 18, 2009

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oil pump or the pumps ds. im pretty sure it was quite common on the mod cars.

rj95svt · Dec 18, 2009

Does the car have underdrive pullies? I have read where underdrive pulleys can cause problems with the oil pumps on some mod motors. The oil pump on a mod motor is driven directly off the crankshaft and underdrive pulleys for a mod motor space out the hb on the crank.

I'm not sure but if it is a oil pump you should be able to pull the front cover and timing chains and gain access to it without pulling the motor or k member.

fiveoho · Dec 18, 2009

rj95svt said:
Does the car have underdrive pullies? I have read where underdrive pulleys can cause problems with the oil pumps on some mod motors. The oil pump on a mod motor is driven directly off the crankshaft and underdrive pulleys for a mod motor space out the hb on the crank.

I'm not sure but if it is a oil pump you should be able to pull the front cover and timing chains and gain access to it without pulling the motor or k member.

stock pullies.

which would be more of a chore if it were to be the pump: dropping the k member or taking out the chains?

revhead347 · Dec 18, 2009

rj95svt said:
Does the car have underdrive pullies? I have read where underdrive pulleys can cause problems with the oil pumps on some mod motors. The oil pump on a mod motor is driven directly off the crankshaft and underdrive pulleys for a mod motor space out the hb on the crank.

I'm not sure but if it is a oil pump you should be able to pull the front cover and timing chains and gain access to it without pulling the motor or k member.

That doesn't make any sense. The oil pump has nothing to do with the pullies.

More than likely it's a bad sending unit.

Kurt

HankyGT · Dec 18, 2009

^^ Negative, the mod pulley is actually part of the harmonic balancer as it is all one piece. Aftermarket ones can not be balanced to the same harmonic levels and can cause movement in the crankshaft putting stress on the pump shafts. Especially common on the 4v cars.

I would also put $ on the sending unit or the gauge itself as ford's junk ass gauges are basically on-off switches. Likely the unit. If you break a shaft, you won't have a reading at all and the lifters wont pump up, so you'll have clatter at idle.

I'd spend $20 on a junk sunpro mechanical gauge, hook it up and see what it's reading...then figure out your options.

fiveoho · Dec 19, 2009

from what ive been googling and searching for in forums, it seems the sending unit is fairly typical to be the problem, BUT- my gauge did move . it went from the complete bottomed out reading ( car off ) to reading just under the red line of no oil pressure. basically it moved, just not to the safe zone. so that being said, can it still be the sending unit? please say yes.

also-

the rough idle that i got when i initially started it up...its never done that. could that be associated with a oil circulation problem ( if thats what it is ) or is it just most likely coincidence it being pretty cold and damp tonight along with not being started in a week? car is in a garage but not a insulated one. block walls, open rafters and gravel floor

HankyGT · Dec 19, 2009

no, the gauge can move and still have a screwy sending unit.

I'd associate the rough idle from sitting for sure, possibly moisture on the MAF..I've always had issues during the winter esp if it sat outside

rj95svt · Dec 19, 2009

I would do the sunpro mech. gauge as well just to make sure. Then if you have good oil pressure just replace the stock sending unit. You can just throw on a new sending unit and give it a try also but if it doesn't change you will need a mech gauge just to verify the problem. The stock gauge can read 0 and your liable to have 10-20lb of oil pressure.

If you do have a oil pump problem the chains and front cover have to come off. The oil pump is driven off of the crank snout just behind the timing gears. Those gears have to come off to get the oil pump off. so I don't think dropping the k member helps anything.

Hanky is dead on about the pulleys. I couldn't remember but it does seem the problem is worse on 4v motors. However you can buy aftermarket balancers that are smaller diameter that do not cause any problems.

revhead347 · Dec 19, 2009

HankyGT said:
^^ Negative, the mod pulley is actually part of the harmonic balancer as it is all one piece. Aftermarket ones can not be balanced to the same harmonic levels and can cause movement in the crankshaft putting stress on the pump shafts. Especially common on the 4v cars.

Ok, I guess tha does make sense. Learn something new everyday.

Kurt

fiveoho · Dec 19, 2009

i really hope its just the sending unit. a pump install sounds like a major expensive task.

a few people ( some being mechanics ) told me that i may have simply not given it enough time to build up pressure to read on the guage? they stated since it was cold and sat for a week that 7 seconds may not have been enough . does that sound right? . my 95 could sit for two weeks and be started on a 30 degree day and the oil pressure guage would shoot right up - totally different setup im guessing? also, my 98 4.0 sohc explorer with 177,000 miles soon as i hit the key, oil pressure is right there

Adam95GT · Dec 19, 2009

fiveoho said:
i really hope its just the sending unit. a pump install sounds like a major expensive task.

a few people ( some being mechanics ) told me that i may have simply not given it enough time to build up pressure to read on the guage? they stated since it was cold and sat for a week that 7 seconds may not have been enough . does that sound right? . my 95 could sit for two weeks and be started on a 30 degree day and the oil pressure guage would shoot right up - totally different setup im guessing? also, my 98 4.0 sohc explorer with 177,000 miles soon as i hit the key, oil pressure is right there

id buy a cheapo mechanical gauge and check as stated above... yea a pump can be an expensive task... but its alot less then if you took someones advice and let it run with no oil up top...

Black95GTS · Dec 20, 2009

fiveoho said:
i really hope its just the sending unit. a pump install sounds like a major expensive task.

a few people ( some being mechanics ) told me that i may have simply not given it enough time to build up pressure to read on the guage? they stated since it was cold and sat for a week that 7 seconds may not have been enough . does that sound right? . my 95 could sit for two weeks and be started on a 30 degree day and the oil pressure guage would shoot right up - totally different setup im guessing? also, my 98 4.0 sohc explorer with 177,000 miles soon as i hit the key, oil pressure is right there

What are you using for oil? My 2001 F150 takes 5w20 per the manual, and in the winter time it can take 5 minutes before the gauge reads normal oil pressure. The poster that commented saying Ford gauges are "on off switches" is dead nuts right. If it bothers you, switch to 10w30 and I bet you'll have pressure right away.

Adam

fiveoho · Dec 21, 2009

Black95GTS said:
What are you using for oil? My 2001 F150 takes 5w20 per the manual, and in the winter time it can take 5 minutes before the gauge reads normal oil pressure. The poster that commented saying Ford gauges are "on off switches" is dead nuts right. If it bothers you, switch to 10w30 and I bet you'll have pressure right away.

Adam

5w20 also. kinda makes me feel better it takes your truck that long for the needle to move up. maybe its fine . it was cold that night

i am going to put a mechanical gauge on it tonight tho and see what that tells me. how much pressure should it make on a cold start?

Bosko5.0 · Dec 21, 2009

anywhere between 40-65psi. You might want to use a oil pump primer Summit Racing SUM-901011 - Summit Racing® Oil Pump Primers - Overview - SummitRacing.com So you don't have to run the engine.

rj95svt · Dec 21, 2009

That primer will not work on a mod motor.

fiveoho · Dec 21, 2009

replaced the sending unit and the needle came right up - phew!

thanks guys for all the input

Adam95GT · Dec 22, 2009

awesome glad it wasnt serious

rj95svt · Dec 22, 2009

I was hoping that was it. I'm glad you had a simple fix!

no oil pressure. help please

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