Before I replace the pump, there's one easy thing to try:

Does anyone know if the engine oil cooler thermostatic valve on the filter adapter (if stuck) can interrupt oil flow to the engine? If so, would it cause a loss of pressure (or increase) as measured on the gauge?

I can try disconnecting the cooler and/or remove the thermostatic valve and replace it with the original plug. I find it curious that some of the engines with coolers didn't have the thermostatic valve and wonder if dealers removed them for this very reason. <img src="/forums/images/graemlins/confused.gif" alt="" />

Frank

Don't know the definitive answer, but your experiment sounds like a worth-while -- and fairly easy -- one to do <img src="/forums/images/graemlins/kewl.gif" alt="" />

Eric W.

I have a spare filter adapter, so I just spent some time looking at the oil flow passages. It seems entirely possible to me that it could be the issue.

As confirming suspicion, it seems strange that oil pressure is fine when cold, but decreases as the oil warms up - with a corresponding spike in oil temperature - possibly because the thermostatic valve is not allowing full flow into the cooler and back-pressuring the pump, causing pump cavitation and heating the oil more than is otherwise normal.

I don't remember removing the thermostatic valve for cleaning when I cleaned the adapter housing for re-installation..... maybe, maybe not.... so it might be gunked up.

I'll sure try it tomorrow..... might even remove the cooler lines and install the original plugs in case the oil cooler is somehow plugged.

Frank

Thanks, Phil -

When I started this, I never intended that it would become so involved, believe me. <img src="/forums/images/graemlins/lol.gif" alt="" /> The original idea was a failure and has now morphed into something far different than I envisioned.

Frank <img src="/forums/images/graemlins/cheers.gif" alt="" />

Let me know if you need another pump, Frank.

Thanks, Larry - it's beginning to look that way. This morning I removed the thermostatic oil valve.... looked ok.... removed the oil cooler and lines and found a few flecks of aluminum particles in the cooler.... replaced the OE plugs in the oil filter adapter and started the engine. Oil pressure was a little better, but still dropped as the engine got hot. Lifter tapping is pretty noisy now.

When I have some time, I'll remove the oil pump and see what I find.... if anything.

Frank

Hi Frank,
I couldn't find your thread, it is up top above my scan. I just don't get enough time to look around at all the sites I am active on anymore.

High oil temps are caused by friction. Something is causing the heat and thinning will result. What kind of temps are you seeing in how much time?
I doubt the pump is the cause especially if it was in the previous version of this engine.
You mentioned a tight main bearing, How and why did one tighten? Even still if the crank spun free by hand with no tools on the snout it should be fine.
You mention no oil to the top end, this is not good. Is this both sides?
If the pressure gauge is after the filter and cooler. It would be nice to get one before the filter. Many are before the filter originally. This can help locate an issue but not all of them.
The thermo valve should not induce a drop in pressure, but if there is lack of flow in the cooler this will. As the thermo closes it forces flow through the cooler expecting little restriction.
This is where the value in this case of having say two gauges to isolate the drop in pressure.

You mention packing the oil pump with something, why? The days of using goo in the pump or Moly as an assembly lube are long behind us.
As soon as a pump is turned anything in it is displaced out into the passages blocking flow from the pump causing cavitation.
And if moly is used, that does not pass through a filter causing undue restriction forcing the bypass to open. A new engine is not a good time to have a filter in bypass.
Now I have not been able to read all the posts here so I may be barking about stuff I should not be. I should be back down in the shop trying to finish an EVO for this weekends event.

Hi Charlie -

Once coolant temperature comes up, oil temperature follows, but it seems to me that oil temperature continues to climb - yet coolant temperature does not. Coolant temp levels at ~ 200?F. After that, I can feel oil temperature climb by touching the dipstick handle, watching the oil pressure drop and hearing lifter clatter get louder.

Most of the lifter noise is on the driver side, but on the last startup, it seemed to start on the passenger side also.

I did pack the pump with assembly lube to try to avoid a long priming time. Everything seemed fine during the first 20 minutes of high-idle warmup, after which I changed the coolant, oil and oil filter.

I then warmed it up again and went for a drive. All was well for maybe 15 miles until the engine seemed to lose power and I saw no oil pressure. Ever since then, I've had the oil delivery issue. The only way I know the top end is starving is because of the noise - I haven't yet removed the valve covers.

I installed the same lifters that were in the engine when the blower went bad - perhaps they had some debris in them, but I wouldn't think that would cause pressure to drop. Anyway, they were fine during the first warmup.

When I installed the main studs, I did not follow ARP's advice and align hone the main bores. All except the rear bore showed .002" clearance with plastigage - the rear one showed .001"... tight, but within standard spec. I oiled the crank with 30W, retorqued and turned it by hand and it felt fine - so I didn't align hone the main bores.

I've tried changing the oil and filter a second time with no change.

I've now removed the oil cooler and thermostatic valve - same results - so that is not causing a blockage.

The pressure gauge is before the filter on the 3.0L Montero adapter, so it would appear that the problem is in the pump. The assembly lube may have caused the pump relief valve to hang, but I know several local engine builders who pack pumps with the stuff and do not experience problems.

This same pump was new 7000 miles ago and on initial startup the relief valve hung closed (or nearly so) and oil pressure spiked to 100psi - took a while to come down and I remember being concerned about bursting a filter at the time. During this rebuild, I took the pump apart, cleaned it and checked the clearances.... it was tighter than standard spec on side clearance, but I figured if it was ok before, it would be ok now. I guess not.

The next thing is to pull the filter adapter and see what it looks like. If it looks ok, I plan to replace the pump and see what happens.... and hope the heat hasn't ruined anything.

Frank

Loosing power could have been a seizure.
These SOHCs can have an odd tendency for lifters to clack.
My Mighty max can not be driven down a 3 mile hill without sounding like it is going to throw a rod. Similar if I park on a hill, when I fire up the lifters have collapsed, clack real bad for 10 minutes. It has pressure according to the factory gauge but I would swear it doesn't from the sounds it makes. But I get no issues with the heat from towing.
I have heard about this from the dealer also.
I do not get these issues with my DOHC engines. Odd in my mind.
You assembly lube may dissolve into the oil, it should not have been an issue. Using grease is the issue. I just use oil in the pump.
100 psi is not an issue, 150+ is. My 4G63s run over 100 psi every day and my 72 Colt pegs an 80# gauge whenever it is cold. I have seen warm 4G63 without balance shafts over 100 psi especially if they have 20W-50 in them.

Is there any chance of a tight ring end gap? That can make big heat quickly.
Do you have an infrared thermometer?