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Early (83) oil pump on late (86) block = FAIL???


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Kind of a cross post from rennlist, because I imagine collectively you guys have more experience building motors from random parts.


My issue is that my new motor gets no oil pressure. None. It is not the OPRV... I am literally getting no oil at all coming from the pump. I now run a 951 filter housing with an external oil cooler and get no oil coming out the supply line to the cooler, nor does any pass the face of the OPRV even as evidenced by the fact that the assembly lube never gets washed away from the face of the piston. I swear the pickup is good as it was hot tanked, thoroughly inspected, and installed by the book. Even compared it to my old motor and I am sure I did it right. While talking today with a local 944 guy (Tom) and looking at the car, we were discussing the oil pumps. The pump I put on my car was from an early car, an 83 to be exact with an 81 stamping date on the pump. The motor I am installing on is a 86 block with the matching 86 crank.


What Tom pointed out was this from the WSM: "Various modifications have been made on the oil pump and crankcase beginning with 1985/2 models. Consequently the new oil pump, part number 944 107 014 08, must not be installed in older engines."


Technically I have not violated this proviso as it only implies incompatibility in one direction. However, perhaps a broader interpretation would imply no crossover between early and late oil pumps and blocks.


The existing part numbers in question, which are old numbers since these are factory original oil pumps:

83 pump: 944 107 104

87 pump: 944 107 111


Pelican lists two distinct part numbers for buying a new pump:

944 107 014 09 for build dates through 06/84

944 107 014 11 for 07/84+


This does imply some difference between the two, and I assume 07/84 to be the cutoff for 85.5 production.


Sooooo... the million dollar question is: Does this mean I need to swap out the early oil pump for a later one?


I am prepared to do so this week in order to make a double points race this weekend. I have already missed too many weekends and have a major craving to race. I appreciate your comments as we have tried everything else to get pressure on it as is, with no luck.

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30 psi on the dipstick, put a tube down the filter housing and turned the motor in reverse to prime the pump, tons of oil in the pan, quadruple tightened the crank bolt. I did just about everything I could find from searches on rennlist. When I put pressure on the case, it will hold it until I pull the hose, even if a minute or more... so it is not leaking down or anything.


I've talked to a bunch of people online and at the track yesterday and everyone else followed the same diagnostic path I did. I also feel confident I did the pickup tube correctly.

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I called up to Fordahl in Seattle, and though Greg was busily trying to get out of town, his henchman asked him the question regarding 83 oil pump fitment onto an 86 motor.


The answer I received: NO.


May not be cannon but Greg has a ton of experience, and given I have no better ideas, the pumps are getting swapped out tonight. Here's hoping!

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The only different that I can tell and have seen between the early and late oil pumps is the castings for the belt tensioners. The early oil pumps have a long boss that the timing belt tensioner bolts to. The later pumps do not have this boss because the tensioner assy does not use it. Actually, that boss causes interference. I have an 83 engine which I put an 87 944S oil pump on. I had the infamous no oil pressure issue and swapped out the pump while I was inspecting the pick up and oil pump. Using the later oil pump, I used a spacer to act as the cast boss. It is still holding strong.


So, I don't see any difference in performance between the oil pumps. The difference is the castings.


For priming, I will remove the OPRV and thread a piece of tubing into the port. Then I use a gear lube bottle to squeeze the oil into it. Another trick is to poor oil directly into the center tube of the oil filter. This will go directly to the oil pump as well.


Sorry your having problems. There seems to be a lot of oil pressure problems going around.

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There is a big difference in the oil pumps. It's the outside edge which seals against the block. Early and late have a different shape and if they don't match the block, AIRLEAK!!! No suction-no pressure.

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OK, I got it!!!!


Rebuilt the 87 pump with a new seal and installed it yesterday. Not really fun with the engine in the car, working on the pan bolts from underneath. But I got oil pressure, and started it.


Unfortunately, it will start but doesn't want to idle very nicely. If I give it a little juice and hold it at 1200-1400, it will stay running, but let off the gas and it dies.


I have tomorrow afternoon and evening to get it running and onto the trailer for the track on Friday. Greg F should be there so at least I will have an expert to ask questions of. I already owe him for answering my question about oil pumps the other day. If I get too greedy I might get a bill


Thanks guys... I am stoked, even if it isn't perfect yet. Just have to figure out why it won't idle, then let it run a bit to warm up and break in. Maybe a quick spin around the block even.

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