oil pressure????

[mike4089]

well got my clutch all straightend out drove the jeep down the road for the first time and it shifted nice and smooth.....however the oil pressure was bothering me....when the motor is cold it has plenty of pressure at first start up 65 lbs.....as soon as it warms up it gets very very low....when you rev it up the oil pressure increases but no where near to what it is suppossed to be......any ideas on what can cause this would be great......

[Mcktiger74cj5]

i got the same thing going with my 304. cant wait till my 360 is done maybe june.

[jeepsr4ever]

When you have a situation like your describing you can have tight bearing tolerances but poor oil pump tolerances. It is also possible that your sending unit is bad, that also follows those symptoms. Try the sending unit and a new oil filter (WIX preffered), midplate with rebuild kit second and lastly if it still isnt fixed try a new timing cover.

[ironman_gq]

is 55 cold and 15 hot idle 35hot cruising ok or should I be looking to bump it up?

[mike4089]

When you have a situation like your describing you can have tight bearing tolerances but poor oil pump tolerances. It is also possible that your sending unit is bad, that also follows those symptoms. Try the sending unit and a new oil filter (WIX preffered), midplate with rebuild kit second and lastly if it still isnt fixed try a new timing cover.


its a direct gauge.....what about the little plunger inside the oil pump stuck open????.....new timing cover???....what goes bad on the cover that will cause that........

[jeepsr4ever]

Sometimes break in lube or vaseline gets behind the plunger and can cause strange issues. Take the spring and plunger out and clean them and re-install.

[dbesade]

is 55 cold and 15 hot idle 35hot cruising ok or should I be looking to bump it up?

Thats what my 304 turns out. 20PSI on hot idle after an oil change... generally its around 15-17psi idle. FSM says at least 13PSI at 600RPM 37PSI min above 1500.

-Dave

[mike4089]

what about cam bearings????......this motor is brand new..........

[jeepsr4ever]

Hard to say what condition your cam bearings are in I dont know enough information about the break in temp, time of break in or mileage on the motor.

[mike4089]

there is like 1 mile on the motor its only been started a handful of time.........

[jeepsr4ever]

Are you using a old timing cover or a new one? sounds like you may have excessive clearance in your oil pump.

[mike4089]

it is an old timing cover............what exactly should i buy for the oil pump.....i do know that when i put the gears in for the pump and put the plate on...you could see where the gears rode on the plate but it didnt seem to bad.........

[jeepsr4ever]

Sounds like you need a basic oil pump/timing cover to fix your pressure woes.

[mike4089]

what role does the timing cover have in the oil pressure...?????i know the pump gears ride inside of it but other then that what goes bad in them......?????

[82Waggy]

The inside walls that the pump gear wipe past get worn or scored, opening up gear clearance and reducing pump efficiency.

Gear end clearance is also critical to pump performance.

[jeepsr4ever]

What happens is that the pump cavity itself wears out. It is made from a high silicone aluminum that can wear rapidly due to the oil getting to the pump before it gets to the oil filter. This is the basic issue with these AMC pumps. We are battling this issue with a ceramic coated oil pump housing (thats in the future here) and with our nickel plated oil pump housings. the Ni helps out alot and we are making our own pump using a removable pump as an update to the nickel unit however it is many months away. When you take your oil filter adaptor off check the see how far the edge of the gear is from the pump cavity wall. Using a spark plug shim set you shouldnt be more than .005". If you have greater clearance than that you should look to a new or used pump housing.

[mike4089]

yay...i found my problem......the small oil gear was in the pump upside down.....gonna put it all back together today and hopefully that should solve my problem...........

[Goose]

upside down? :shock:

[82Waggy]

yay...i found my problem......the small oil gear was in the pump upside down.....gonna put it all back together today and hopefully that should solve my problem...........

Don't think there is a difference, unless your original gear is worn on one end.

You mentioned you could see where the gears rode on the cover plate. Assuming you mean the oil filter adapter, you should use a honing stone to smooth the surface the gears ride on, or better yet, install the stainless mid plate that Bulltear sells (smooth the filter adapter in this case too for a good gasket sealing surface).

Since you are seeing this kind of wear, chances are your gear end clearance is loose. If you can see wear on the end of the gears, either change them out or clean them up and set up proper end clearance. If the timing cover cavity walls are worn, you need a new timing cover.

[mike4089]

the timing cover housing was in really good shape....there wasnt any wear or movement on the gears....the adapter plate had some scoring on it but its not really all that bad.....the oil gears have the two dots on them that are suppossed to be together....one gear was upside down im guessing the dots are there to for a reason....we will find out when i put it all back together i guess..........

[82Waggy]

Scouring on the adapter plate can result in a significant loss of pressure. You should seriously consider adding a stainless mid- plate. The dots on the gears are insignificant.

[hotratz]

.......The dots on the gears are insignificant.

I thought that's how you time your pump... :-| :mrgreen:

Seriously though. I just had my gear out and it doesn't have the dots you speak of. I did notice the scuffing on the face of the adaptor plate but it seems to be superficial. When I drag my fingernail across them it doesn't catch. The gasket thickness on the cover is critical on all oil pumps. The one I replaced measured .009. Don't really know what the norm is.

[82Waggy]

.......The dots on the gears are insignificant.

I thought that's how you time your pump... :-| :mrgreen:

Seriously though. I just had my gear out and it doesn't have the dots you speak of. I did notice the scuffing on the face of the adaptor plate but it seems to be superficial. When I drag my fingernail across them it doesn't catch. The gasket thickness on the cover is critical on all oil pumps. The one I replaced measured .009. Don't really know what the norm is.

I leave it to you to determine how bad the scoring on the pump is, since we can't see it. #-o

Aside from scoring, gear end clearance dimensions have a lot to do with how much bleed down past the gears there is, and therefore effects output efficiency.

There are several sources for tech info on this subject, including the TSM and Performance American Style. The stock specification for gear end clearance suggests that the gears should protrude .002" - .006" out of the housing. Assuming a standard .0095" thick pump cover gasket, this yields .0075" - .0035" gear end clearance. According to PAS, for a performance application the pump housing end should be milled so that the gears protrude .006" - .007", yielding about .0025" gear end clearance when the filter adapter (pump cover) is installed with an .0095" thick gasket (slightly thinner when compressed.

There used to be thinner gaskets available to aid in establishing the desired clearance without milling the housing, but I beleive only the .0095" thick gaskets are now readily available.

IMO: if you are going to tighten up the tolerances as described, you should consider using the stainless mid-plate for the gears to ride on. It is effective at extending the life of any pump cover.