90 4.0 Oil Pressure Relief Valve - Where is it?

BoneStock · Nov 13, 2005

Anybody know where the oil pressure relief valve is located on a 1990 4.0L? I've got a lot of oil coming out, the oil pressure guage is reading high and I've already replace the valve cover gasket, main seal, and the oil filter o-rings. My last guess it the pressure relief valve, but I can;t find it right away. It's my last chance. I'm at 180k and think it might be getting close to that time that I have to swap motors.

Thanks!

wilcharl · Nov 13, 2005

It has one? i always thought the relief was it blowing a gasket or a seal I was flying a rental plane once and it kept blowing the crankshaft seal (behind the prop) ... told the id-10Ts that i was renting it from that hte crankcase pressure was to high... they insisted the seals were bad and went thru three seals b4 they agreeed with me...

langer1 · Nov 13, 2005

BoneStock said:
Anybody know where the oil pressure relief valve is located on a 1990 4.0L? I've got a lot of oil coming out, the oil pressure guage is reading high and I've already replace the valve cover gasket, main seal, and the oil filter o-rings. My last guess it the pressure relief valve, but I can;t find it right away. It's my last chance. I'm at 180k and think it might be getting close to that time that I have to swap motors.

Thanks!

You got lots of oil comming out where?
Could your oil pressure sending unit be leaking and giving a bad reading.

yellowxj · Nov 13, 2005

IIRC the pressure relief valve is inside the oil pump, so it doesnt put too much oil pressure out...a spring keeps tension on valve, when I put my new pump in a mechanic friend of mine suggested that we shim the spring a little bit to bump up the pressure, I think it turned out that we had to tap in the plug that holds the spring in. A little adjustment turned into a lot of oil pressure. Used to hit 80+ on the gauge. Blew out two factory oil pressure sending units then went to a mechanical gauge. Guess as the spring aged it let the pressure back to more normal.

BoneStock · Nov 13, 2005

My oil pressure sending unit looks good. Actually had that swapped out last year. I think it's the only "clean" thing left in there! All the oil found is below that point.

Thanks for the info guys. I'll keep trying.

Know a good place to get a good H.O. cheap?

langer1 · Nov 13, 2005

BoneStock said:
My oil pressure sending unit looks good. Actually had that swapped out last year. I think it's the only "clean" thing left in there! All the oil found is below that point.

Thanks for the info guys. I'll keep trying.

Know a good place to get a good H.O. cheap?

If it's the only thing clean then it's leaking.

ifixjeeps · Nov 13, 2005

Sounds more like a PCV system problem.Check the hose/line between the valve cover and the air box for a restriction.

BoneStock · Nov 13, 2005

I wish it were as simple as the PCV (good idea, but I checked that already) or the sender unit (it looks clean in 360 deg). That's why my last guess has been the pressure sender unit - I can't see that readily - now that I know it's in the oil pump. I'm bringing it in Monday and want to point them in the right direction since I've already ruled out a large number of things (and I don't want to pay them for unnecessary troubleshooting!). I hope that's it beacuse otherwise I think it's time for a new engine...

xj9140 · Nov 13, 2005

Do the older non ho 4.0's share the same pump as the 91-up, 96-up? I have a non-ho oil pump @ my disposal and want to modify it to produce moure oil psi. My current motor is 1999 ho.

langer1 · Nov 13, 2005

BoneStock said:
I wish it were as simple as the PCV (good idea, but I checked that already) or the sender unit (it looks clean in 360 deg). That's why my last guess has been the pressure sender unit - I can't see that readily - now that I know it's in the oil pump. I'm bringing it in Monday and want to point them in the right direction since I've already ruled out a large number of things (and I don't want to pay them for unnecessary troubleshooting!). I hope that's it beacuse otherwise I think it's time for a new engine...

I have see those dam senders leak for a few seconds and stop.

90 4.0 Oil Pressure Relief Valve - Where is it?

BoneStock

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wilcharl

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langer1

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yellowxj

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BoneStock

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langer1

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ifixjeeps

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BoneStock

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xj9140

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langer1

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