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restricted oilflow to head.


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My MJ has a knock while driving, and I thought it was a collapsed lifter, but I pulled the valvecover, and ran it, and she's only getting oil through the pushrod and rocker on one valve. It's an 89' renix 4.0. It doesn't have the full gauge cluster, but the oil pressure dummy light only comes on at super low idle. (like 500 rpm) I had the oilpan off, when I replaced the pan gasket, and rear main, and everything looked pretty clean. It did sit for like 3 years between being crashed, and me getting it together and drivable. I just got her up and running and on the road like a week ago. any Ideas? Thanks guys!

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Which cyl is still getting lubrication? I think it is time to throw a pressure guage on there. What kind of wreck was the truck in? Any impact to the right front area?

It's the number 5 intake valve. Where is the pressure port on the renix head? I can borrow a gauge at work tomorrow. Where should I go from there? It was wrecked hard in the left front. bent the axle, and put a 3 inch round, half inch deep dent in the side of the oilpan where the sump is. I wouldn't think that would affect the pickup, but I'm not positive.

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I agree get a pressure gauge on it to see what you really have however it sounds like your oil pump is on it's last leg seeing how the higher rpms gives it enough pressure to keep the idiot light off. If the pressure is ok then maybe your push rods are clogged up or there is an obstruction in the oil pump restricting flow. If it were me, I'd start with cheapest and work my way up.

 

1 Hook up a pressure gauge to it and verify pressure. If good go to 2 and if bad go to 3,

 

2 Pull pushrods and check if they are clogged. If not,

 

3 Pull the pan and check/replace oil pump.

 

I would have thrown check oil filter in there after check pressure but I'm assuming it is new since you replace the oil after the pan drop.

 

 

:cheers:

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It's the number 5 intake valve. Where is the pressure port on the renix head? I can borrow a gauge at work tomorrow. Where should I go from there? It was wrecked hard in the left front. bent the axle, and put a 3 inch round, half inch deep dent in the side of the oilpan where the sump is. I wouldn't think that would affect the pickup, but I'm not positive.

 

And the plot thicken's. The dent shouldn't effect the sump but if the impact jared the pickup tube, it may have broken the seal to the pump, allowing the pump to suck air instead of oil. That would give you the low idle idiot light as the higher rpms pulls hard enough to get oil but is still not producing a lot of flow.

 

 

:cheers:

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I agree get a pressure gauge on it to see what you really have however it sounds like your oil pump is on it's last leg seeing how the higher rpms gives it enough pressure to keep the idiot light off. If the pressure is ok then maybe your push rods are clogged up or there is an obstruction in the oil pump restricting flow. If it were me, I'd start with cheapest and work my way up.

 

1 Hook up a pressure gauge to it and verify pressure. If good go to 2 and if bad go to 3,

 

2 Pull pushrods and check if they are clogged. If not,

 

3 Pull the pan and check/replace oil pump.

 

I would have thrown check oil filter in there after check pressure but I'm assuming it is new since you replace the oil after the pan drop.

 

 

:cheers:

Filter is good. I am simple as head work goes, but not that simple! :fs1: I pulled cleaned and reinstalled both number 1 rockers, and pushrods. still no flow. I didn't see any excessive crud or sludge in the pushrods, so the problem is lower than that. I guess I should have checked the pump out when I did the pan gasket, and rear main!

 

I also had the pickup tube out. I put it back in the same way it came out. it is a metal to metal seal, right? Could I have lost a seal that should be there? Thus causing it to suck air?

Also, what is the track record on the lifters in these motors? Is that something to look at, Or are they more of a last resort?

Where is the pressure port, and how much pressure should I be looking for/how much is not enough! Thanks guys!

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If the dent was fairly high up on the side of the pan where it sticks out, then you cracked the oil pump. The dent is from the UC mount on the axle hitting the pan. I have seen this at least a half dozen times over the years working on Jeeps. If you haven't run the engine too much, you might be able to drop the pan (again) and just change the pump. The lifters get oiled from the main oil gallery, which then pump the oil up the push rods to the rockers.

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I also had the pickup tube out. I put it back in the same way it came out. it is a metal to metal seal, right? Could I have lost a seal that should be there? Thus causing it to suck air?

Also, what is the track record on the lifters in these motors? Is that something to look at, Or are they more of a last resort?

Where is the pressure port, and how much pressure should I be looking for/how much is not enough! Thanks guys!

 

Here's a note from my repair manual.

 

CAUTION: DO NOT move oil pick-up pipe in pump body. If oil pick-up pipe is moved, pick-up pipe must be replaced to ensure an airtight seal.

 

The pressure port is just above the filter where the sender is screwed in. Far as the pressure, I can't seem to find it but will post it when I do.

 

:cheers:

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I also had the pickup tube out. I put it back in the same way it came out. it is a metal to metal seal, right? Could I have lost a seal that should be there? Thus causing it to suck air?

If you had the pickup tube out and just stuck it back in, you don't have a seal.

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Here's a note from my repair manual.

 

CAUTION: DO NOT move oil pick-up pipe in pump body. If oil pick-up pipe is moved, pick-up pipe must be replaced to ensure an airtight seal.

 

Can I RTV that, or do I have to replace it?

Well, either way, that sounds like a cheap fix! I'll do that, and I'll check the pump for damage/wear while I'm in there. I'm glad I was smart enough to use a lube locker on the pan when I did the rear main! What's the feeler/clearance for the oil pump? I have a Grand cherokee manual, but they never had a renix, so some parts are useful, some are not! Thanks for the quick responses/help guys!

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Can I RTV that, or do I have to replace it?

Well, either way, that sounds like a cheap fix! I'll do that, and I'll check the pump for damage/wear while I'm in there. I'm glad I was smart enough to use a lube locker on the pan when I did the rear main! What's the feeler/clearance for the oil pump? I have a Grand cherokee manual, but they never had a renix, so some parts are useful, some are not! Thanks for the quick responses/help guys!

 

If it was me and to prevent future headaches, I'd just put a new pump in there and be done with it. However, here is the specs and notes on it.

 

Gear end clearance .004-.008 (.10-.20)

 

Gear-to-body clearance .002-.004 (.05-.10)

 

Apply permatex No. 2 to pick-up pipe prior to installation. Using pipe installer (J-21882), install pick-up pipe.

 

Not sure what that pipe installer is. :dunno:

 

:cheers:

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If it was me and to prevent future headaches, I'd just put a new pump in there and be done with it. However, here is the specs and notes on it.

 

Gear end clearance .004-.008 (.10-.20)

 

Gear-to-body clearance .002-.004 (.05-.10)

 

Apply permatex No. 2 to pick-up pipe prior to installation. Using pipe installer (J-21882), install pick-up pipe.

 

Not sure what that pipe installer is. :dunno:

 

:cheers:

Thanks again bud! :banana: You are better than Hanes and Chiltens combined! jamminz.gif

(And the pipe installer is my right hand!)

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Thanks again bud! :banana: You are better than Hanes and Chiltens combined! jamminz.gif

 

Now I wouldn't go that far.

 

I do love my Mitchell repair manual on CD though. Was worth every penny. About $6 off ebay.

 

EDIT: Here's the oil pressure per the above manual.

 

Normal oil pressure should be 37-75 psi maximum above 1600 RPM. Minimum oil pressure should be 13 psi at 600 RPM
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EDIT: Oil pressure should be around 30 (+/- 5) at idle.

:cheers:

Ummm ... no.

 

Oil pressure should be 13 psi minimum at idle, and 37 to 75 psi above 1600 RPM. That's per the factory service manual.

 

Yeah I fixed it with the later post just forgot to go back and edit the earlier one. :doh:

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  • 2 weeks later...

OK, replaced my pickup tube, and that didn't fix it. Brought home a pressure gauge from work, and I have oil pressure all day! 40 lbs at idle, 70 when I open the throttle. I only had the rear bearing cap off when I did the rear main, and it looked fine. (No scoring, chips, gouges, etc) So I'm assuming the others are fine too. Where should I go from here? I really don't want to pull the head unless I have to, and I can't afford to throw parts at a problem! Thanks guys!

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