429 little or no oil pressure

[Vinny]

Hello all.  I recently rebuilt my 65 429.  It had no front cover on it so I swapped in one I had from a 66 429 along with the distributor. When I rebuit the motor, I installed new oil pump gears.  I primed the oil pump and was getting good oil pressure (I installed a gauge in the dash).  Every once in a while there is no oil pressure at start up.  I pulled the distributor again and primed the oil pump until there was good pressure. Recently, I had to drop the gas tank because I need to do rust repair on the trunk.  After not being started for 4 months, I started the motor up last night for the first time since September.  Again, no oil pressure at all.  I was even hearing clatter from the rockers.  I shut the engine down immediately.  My question is this:  Why am I getting no oil pressure?  I do not want to prime the pump everytime I start the car!.  Please help with any advise you guys may have.

[greg surfas 15634]

Vinny,
It sounds like the oil pump is loosing its prime during extended shutdowns.  The most likely places this might occur would be either in the pick-up tube in the pan where it goes into the block (gasket), the timing cover where the pick-up is fed to the oil pump through the block to cover gasket, or possibly the oil pump relief is sticking open, causing the loss of prime.
If there are no external leaks then these seem like the most likely.
Greg

[Vinny]

Thanks for the response.  How do I check the oil pressure relief valve?

[John Morris #23947]

I had this problem once. I installed a new oil pump in a 455 Buick, using only a gasket. No oil pressure! I had to pull the pan and pump, used thick gooey gasket maker on both sides of the oil pump gasket, whalla! 60 psi!!

[greg surfas 15634]

Vinny,
The pressure relief is that spring and plunger behind the hex head plug in the side of the oil pump.  I am not sure if you can get it out with the oil filter extension installed, but if you can, pull out the plug, then there will be a spring and plunger behind it.  I don't believe anything will fly out but pull the plug carefully.  With out the spring, the plunger should move fully in and out without binding.  Since you said there was no problem with oil pressure at any time the engine war running (how about when warm?), if you do not find any roughness in the plunger operation, and there are no external leaks, the only other suggestion, as before was a leak in the pick-up or the timing cover gasket. 
If you cannot pull the plug and plunger out with the oil filter extension in place, you can remove the retaining bolts (4) and drop the assembly down and check it.  Be sure to replace the oil pump gasket. Do not, repeat do not just re assemble the pump cover with some type adhesive.
Greg

[Frank Starr]

Having been through this, I can tell you that this is a lousy design.  The pump is in the front timing cover which is made of cast (die-cast I think) aluminum or some related wonder metal.  If you had looked closely, I sure you would have noticed score and wear marks in the oil pump 'housing', which is simply cored in the timing cover.  It's unrepairable, and new front covers are unobtainium.  They were that way thirty years ago when I rebuilt the 429 in my 64 Fleetwood Sixty Special.  Further, it doesn't help that the pump is located some distance away from the oil pan, instead of being in the pan.

After a full engine rebuild, every morning on starting the oil pressure light would stay on for 4-5 seconds before going off.  Don't remember if I heard the clatter or not, I sort of remember it.

While I'm at it, the 429 is pretty scary to rebore, because the factory puched them out to the max when new.  As I remember, the shop manual advised not to overbore more than 0.010-inch (maybe it was 0.020)!  Well, you can't clean up anything with that kind of limit.  At the time, I was lucky to locate a set of 0.030-inch over pistons, and we took a chance boring the block 0.030 - fortunately, it held.  Had to have 0.030 rings custom made.

The 429 is a bad engine.  IMHO.

Frank Starr, P.E.
CLC Member
Seattle

[greg surfas 15634]

Frank, I wasn't going to respond but I have to.  The 429 engine was and still is one of the most bullet proof pieces of internal combustion devices made.  The components are so under stressed that if taken care meaning changing oil filters and tune-ups they will run trouble free for hundreds of thousands of miles toting around the 5oo pound vehicles they were installed in.
The trouble of wear in the timing cover is not usually from the oil pump (if it has been pumping clean oil) , but in the fact that the water pump and its using the timing cover for part of the water circulation system. 
If assembled correctly the oil pump and oil pick up circuit will not lose its prime, and unless the oil is too viscous for the climatic conditions, oil pressure will be achieved before the engine has rotated more than a couple of times on the starter.
Very often poor mechanics blame their mistakes on the devices they try to repair.
In their research for future engines, the 429 was successfully bored and stroked out to 500 cubic inches by Cadillac Engineering.
Sorry for the rant.
Greg Surfas

[35-709]

I have to agree with what Greg has said, and while maybe not the best engine Cadillac ever put in a car (I feel that honor belongs to the 472/500/425), it is certainly not a "bad" engine.  My well worn '66 429 out of an ambulance was bored .30 over and performed and held up admirably.
   

[Chris McBride]

The trouble of wear in the timing cover is not usually from the oil pump (if it has been pumping clean oil) , but in the fact that the water pump and its using the timing cover for part of the water circulation system.

agreed and =FWIW my 429 recently visited the neighborhood machine shop for a rebuild.   I was very concerned over the condition of that cover since they are extremely difficult to find.  The oil pump area itself was fine.  However, significant damage to the areas around the water inlets was very noticeable and quite ugly.   I’d therefore encourage any members with an aluminum timing cover (or any more modern car with all those aluminum engine parts) to do take a quick stroll through the net on the topic of electrolysis and its corrosive effect on aluminum.

Like most members here, I suspect that I border on obsessive/compulsive in the ritual monitoring and changing of all vital fluids so I disbelieve that the damage was from any simple coolant issue.  The future maintenance dance, consequently, will now include a ritual checking of the coolant for electrical flow, the use of anti-electrolysis additives, a sacrificial anode, and a more systematic cleaning and tightening of all electrical grounds.

http://www.google.com/search?hl=en&q=automotive+radiator+electrolysis&btnG=Google+Search

[Vinny]

Thanks for all the help everyone.  I took a little of everyone's suggestions and got to work on the pump.  I took off the oil filter extension and I cleaned it out with brake cleaner.  I took out the oil pressure regulator and cleaned it out also.  I put engine lube on the gears, oil pressure regulator and spring. Cleaned out the little screen and lubed up that spring too.  Put in a new gasket with just a little film of Permetex and put it all back together.  I primed the oil pump with a drill and got nice pressure.  Started the car and got a sold 30PSI at idle.  Let the car run for about 1/2 hour and it maintained oil pressure at 180 degrees.   I appreciate it all. Now the disk brake conversion is next!

[Big Fins]

I may be a little late coming here, but the oil pressure is regulated by how tight that hex head plug in the oil pump is.

When you removed it for cleaning the pumps interior and regulator plunger, I hope you didn't crank it too tight. 30 psi at a hot idle is too high for a stock 429. 15psi is more realistic with 45-50 being max pressure when the oil is at operating temperature, and running at 2500-3000 rpm's.
The pressure springs are also color-coded for the desired pressure. You also want to have not only the right pressure, but volume of lubricant too. You can have great pressure and too little volume, or vice-versa.

Too high a pressure can result in a bearing being "washed", and possibly spun in it's journal, or the oil being forced through the by-pass and not getting filtered.
Your factory service manual has all the proper pressures noted within it.

Fins

[greg surfas 15634]

Hey guys,
A point of reference.  The oil pressure relief spring on the oil pump for a 66 - 429 is what determines the relief, or maximum pressure a pump will supply.  The hex head plug is just that.  It's purpose  is a plug to hold the spring in place. Either a shim or a different spring would be the way to increase the pump pressure.
Vinny, is that 40 psi after the oil is warm, and if so, what weight oil are you using? If in fact you do have 40 psi of oil pressure as measured at the oil pressure sensor at the upper rear of the block behind the intake manifold, you probably have something installed incorrectly.  Either you did not install a gasket between the oil pump and the filter extension or the wrong relief spring.  The first situation will take care of itself when the pump gears wear through the aluminum of the filter housing, but you do not want that to happen.  Pieces of Aluminum in the gears are quite destructive.
Tell us, what is the oil pressure when the engine warms up at idle and at about 2500 rpm?
Greg

[Vinny]

I am using 10W-40.   When the engine is idle and @ 180 degrees.  The pressure is about 20-25PSI.   It would hit 30 in the beginning, then drop when warm.  I really appreciate all this help!

[greg surfas 15634]

Sounds good to me Vinny,
Let it sit for a couple of days and see if you still have the prime.  I'm glad it was the easiest of all possible problems.
Greg

[Big Fins]

Greg, Just for the sake of argument here. A trained mechanic will know not to overtighten the hex bolt. And yes the springs dictate the pressure. BUT, a novice going in will try to crank down on that hex plug looking for a seat with it. This will increase the pressure as the spring is overcompressed.
The 472 has that bore threaded for quite a ways, and it's real easy to over-run the plug past where it is supposed to be.

I just thought I would clarify so you don't make me to look like I don't know what I'm saying.

Fins

["Cadillac Kid" Greg Surfas 15364]

John,
I just went through this exercise on my 429 last month.  The plug holding the spring seats at the bottom of its "well", and is truly just a plug.  I did, in fact shim my spring for a few more PSI.  You don't overtighten the plug because it will crack the aluminum housing.
Just trying to relay my version of my personal reality.  Not taking credit for nothing.
Greg

[76eldo]

Is all of this in the Cadillac shop manual?  I wouldn't do anything like this on one of my cars without reading everything from a factory manual first.

Brian

["Cadillac Kid" Greg Surfas 15364]

Brian,
If you were specifically asking for a shop manual reference for the oil pump regulator valve plug for the 1966 429 engine that villy was working on it is in the 1966Shop Manuasl under Engine Mechanical on pzages 6-86 through 6-89.
I have been doing this type of work for a few decades, and I would not attmpt anything new (to me) without the appropriate factory literature.
Greg

[Big Fins]

John,
I just went through this exercise on my 429 last month.  The plug holding the spring seats at the bottom of its "well", and is truly just a plug.  I did, in fact shim my spring for a few more PSI.  You don't overtighten the plug because it will crack the aluminum housing.
Just trying to relay my version of my personal reality.  Not taking credit for nothing.
Greg

No harm done. 90% of my experience is on the 472/500 series engines. They are just a bit different from the 429's, but enough to make a difference.
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If you were specifically asking for a shop manual reference for the oil pump regulator valve plug for the 1966 429 engine that villy was working on it is in the 1966Shop Manuasl under Engine Mechanical on pzages 6-86 through 6-89.
I have been doing this type of work for a few decades, and I would not attmpt anything new (to me) without the appropriate factory literature.
Greg


You would be amazed at the ones that do. I could tell hours of stories on the subject.

Go into a Northstar with out a manual, and see if it runs again.........properly!! 

Fins

["Cadillac Kid" Greg Surfas 15364]

John,
I don't think I would attempt to tune the radio, let alone drive a Northstar era Cadillac without SEVERAL manuals at hand.
Greg (the Cadillac Kid)