Engine and Transmission Tech

First, let me say that I have been mining this site for information about this problem, but nothing I have come up with has solved the problem. Basically, I have a 4.0 Rover in my TR8, which is a replacement for the original 3.5 which died due to being overheated one too many times.

I found a donor engine in a '98 Range Rover and took it to my local machine shop for disassembly and inspection. They rebuilt the heads and told me that the camshaft was wiped, but otherwise pronounced that everything was in spec and ready to go. Fast forward about three years, and I finally found the time to assemble the engine and get it back into the car. I used the oil pan and front cover from the old 3.5 as I wanted to stay with a carb and distributor ignition.

Upon assembly, I spun up the oil pump, got the oil flowing and started her up. No oil pressure to speak of. It moved the needle, but barely, not getting near 20 PSI even when cold. Since this time, I have:
1. checked the oil pump for clearance and wear. I will point out that the 3.5 engine was producing the proper pressure, so I am pretty sure that the old pump is in good shape.
2. Pulled and replaced the front cover several times. As suggested in another thread, I laid it on a thick piece of glass to see if there were any high or low spots. It sits totally flush on the glass.
3. Tried several different gauges - all show the same.
4. Re-checked the bearing clearance on mains and rods. They are at .002, which seems to be in spec although I know it could be tighter. I am not adverse to having the crank re-ground if that is what it needs.
5. Checked the oil pickup connection in the pan. It is as tight as I can make it.
6. Upgraded the spring in the oil pump.

I am running VR-1 20/50 with a zinc additive.

One thing: and old mechanic I know said that if you apply air through the valve cover and air, not oil, comes out of the oil pressure connection on the pump (which it does), that there is something leaking in the pickup. I have had this pan off a half dozen times, looking for this but everything seems to be as tight as you can make it. Is there another passage up in there which should be plugged and is not?

The engine starts and runs, compression is good and it doesn't get overly hot. There is a lot of noise from the valve train, I presume from the low oil pressure.

Any thoughts, no matter how off the wall, would be welcome. I would really like to get this project out of the garage so I can start on the next one.

John, .002 is too much clearance on the Buick/Rover bearings. Perfect for Ford or Chevy. See if you can get .001 undersize bearings. Also the Melling or T/A booster plate and T/A adjustable pressure relief valve is highly recommended. Your rocker clearances may be excessive and flooding the top end with oil will decrease pressure also. I don't know your location but Delta Cams and Rocker Arm Unlimited offer rebuilt rocker assemblies exchange.



Edited 2 time(s). Last edit at 06/28/2017 05:53PM by mgb260.

OK. I have heard that before (about the bearing clearance). Any thoughts on where to get such a size? I had figured that I am gonna have to have the crank ground, but would prefer to simply change the bearings, obviously.

As for the rockers, the only thing I haven't replaced are the push rods and I am wondering if they are worn. BUT, I would think that the hydraulic lifters would compensate for any minor wear. When I take the valve covers off, there does not seem to be an excess of oil, just the opposite.

Thanks for the thoughts. I appreciate it.

John, Another thought. Did you prime the pump with Vaseline before start up. Also front cam bearing good? .001 undersize is common for Ford and Chevy. I couldn't find a listing for Rover but, give King bearings a call.

What lifters did you use John?
The wrong ones, ie. Chevy, will expose the oil groove in the lifter under high lift.
This dumps all your oil into the lifter valley.
One way to find an internal oil leak is to pressurize the oil system with air.
Cobble up some fittings to connect an airline to the oil pressure port and run some pressure into it.
You have a fairly large leak somewhere and it should show itself readily.

Cheers
Fred

A while ago there were gaskets being sold for the end cover of the oil pump, that were too thick and destroyed oil pressure.
They should be paper thin.

Ivor

On that test of pressurizing the crankcase that you did... Could the air you saw have come from the distribution end of the system rather than through the pump? If so it doesn't help diagnose.

At .002 you will hemorrhage oil from the bearings. It'll run, but bearing wear will be more rapid.

While you have it down check the diameter of your pickup galley. The bigger that is the better, up to about 5/8"

Target is 10psi/1000rpm, limited on the top end by the bypass spring.

Jim

Thanks everyone for your thoughts. Let me try to answer some of the questions you asked, in no particular order.

I did use the Vaseline to prime the pump and it is moving a lot of oil.

I just called King, and they do NOT offer the undersized bearings for this engine. That would have been too easy.

I have the thinnest gasket I could find on the oil pump. Also, there is no wear whatsoever in the end plate from the gears.

The idea of pressurizing the system from the pump is a good one, but I will wait until I get the bearing clearance settled, which will probably mean having the crank redone.

The guy from King DID answer my question as to why the tighter clearance was necessary. He pointed out that the aluminum components would expand more than the steel ones. Makes sense to me.

In any event, unless I can come up with the .001 oversize bearings, it looks like a bottom end rebuild is in my future. Thank God I'm retired and don't have to worry about some job or other getting in the way.

Thanks for all of the input. If anyone can come up with a possible different source for the .001 oversize, let me know.

Not familiar with rover engines. The ones I worked on had oil galley plugs front and rear. Are yours there and are they tight.

Steve

Oil galley plugs one of the first things I checked. Thanks.

I would look around a little more before getting the bottom end done John.
I agree that 0.002" is too loose. But not enough to cause the severe pressure loss that you are experiencing.
It would be a shame to get the bottom end redone only to damage it with the same low pressure problem.
I know it was mentioned already, the oil gallery plugs are the most suspect. There are 6 of them. Two at either end of the engine and two more at the front of the lifter valley. The two rear ones are obviously ok as you didn't mention oil on your shoes. The other 4 are possibilities. Your block didn't originally use the oil pickup in the block. The pickup tube went directly to the oil pump on the cover.
The reason I mention this is that I have a 4.6 that was never completely drilled. Couldn't prime the pump to save our lives.
If you pull the distributor and spin the oil pump up with a drill you should be able to get a good solid air free flow from your pressure port.
That would eliminate the pickup, pump and oil filter from the list of suspects.
A though just struck me! Tried to duck but still got hit.
Is the oil pressure relief assembled backwards? Piston in first then spring and cap? It assembles both ways nicely.


Live like you mean it
Fred



Edited 1 time(s). Last edit at 06/29/2017 05:28PM by DiDueColpi.

Actually Fred, my experience has been that it can. But YMMV. I've also seen shim material placed under the bearing shells to take up the play. Not that I'm recommending that but...

On the pump, it is acceptable to port the passages and round all corners. That helps. I set end play on the gears so tight that they actually drag a little on initial assembly. Lifters should be a close fit in their bores, you already said you weren't seeing excess oil on the top end. Cam bearings should be a close fit also. Use the 5/8" pickup tube and enlarge the pickup galley to match using a piloted drill, this can be done in the car.

Jim

John, Have you checked to see if the lifters are Chevy rather than Buick/Rover as Fred mentioned. Another issue if wrong oil filter without anti-drainback valve.

Honestly don't know about the lifters. I bought them from Ted at TS Imported. I doubt he would send me the wrong ones.

The rocker arms are OEM Rover parts.

I pulled the front cover yesterday to look things over AGAIN and saw no flaws. Just for fun, I also did a check on the bearings in the old 3.5 engine, which had plenty of oil pressure and they were also .002, so I agree that that is not the problem.

Plan to re-install the front cover tomorrow and check out things as suggested above. I know this is gonna turn out to be a face-palm simple thing, once it's done.

Again, thanks for all of the ideas.

John, Check out this thread on failed front cam bearing:

[www.hotrod.com]

Buick 350 build showing oiling mods and grooved front cam bearing:

[streettechmag.com]



Edited 1 time(s). Last edit at 06/30/2017 03:30AM by mgb260.

Nothing wrong with being optimistic.
But because one engine with .002 bearing clearance is OK does not mean every engine is OK with .002 clearance. There are a great many variables and the oiling system in the Buick V8 and V6 is a known and recognized weakness. There are factors affecting it that, unless you have completely blueprinted the entire engine and every detail of every component you simply cannot know which factors apply.

Knowing the system is flawed, the best approach has been found to be that of minimizing every known factor that can adversely affect oil pressure and delivery. In other words, if you manage to plug enough of the big holes, provide the best reasonable flow to the pump, and help it do it's job any reasonable way you can, that is generally good enough. But you can't really afford to skip anything if you want superior oil pressure as there just isn't that much excess capacity in the system.

You can get lucky, we've seen it happen. Like your 3.5 with .002 bearings. Who knows why that worked? Occasionally it does. But you can't count on it. I certainly would not begin building a Buick engine by assuming I could get good or even adequate oil pressure with .002 bearing clearance, as it is one of the easiest factors to control, and one of the largest areas of leakage, probable THE largest.

Why all the fuss anyway? Well I saw an illustration once of the difference in leakage between .001 clearance and .002 and though you might not think it, the difference is dramatic. The crank pin does not stay in the center of the bearing and it is common for clearance on the pressure side to be .0002, meaning .0008 or .0018 on the opposite side. Well, .0008" isn't going to leak a lot of oil, but .0018" is going to leak considerably more than just double the amount, it's closer to 4-5 times as much. And that times 13 means quite a bit of leakage.

You aren't building a small block chevy. The oil pump does not have the same capacity and the system was not designed for the same flow rates. If you do increase the capacity of the pump, wear increases in the distributor drive gears and front cam bearing and failures occur. So your choice is, either assemble the engine the way the engineers designed it with tight bearing clearances, or resign yourself to a series of band-aid fixes and short engine life.

Jim

Jim, you have convinced me. I have read too many posts by you to even begin to argue with you. Since I am about halfway there, it really doesn't take much to yank the engine and re-do the crank. So, that's what I will do this weekend and get the tolerances where they should be. I got a good "lecture" by the Cust Svc guy at King Bearing as to why the aluminum engines need the closer tolerances, so there is that, also.

And, as long as I have it out, I can do all of the other stuff recommended and thoroughly go through the entire block and try to find other problems.

Like I said before, I really don't have anything else to do, and I really want this car to last a long, long time until I'm too damn old to drive it.

Stay tuned. I will update as I go.

Again, thanks for all of the good information. I WILL get this thing licked!!!!

Persevere, John!

Do a pressure test of your oiling system once you have it apart and look for unexpected leaks. I had one block with a pinhole leak in the suction galley from a casting flaw. Not common but it does happen. With the alloy block, that can be welded. Had I built the engine with that block without finding and repairing it, low oil pressure would have been chronic and bearing life short.

Jim

Jim, you read my mind. That is exactly what I had intended.