RennBod

Having spent some time looking at a friends 944 turbo this evening (oil pressure problem), we decided we were stuck and so thought we might look at a problem I have had of loosing coolant.

We spent ages under the car with the engine running, looking around with an inspection lamp, and eventually found that at the front of the oil cooler, where the oil cooler meets the block, we slowley watched a bead of coolant form from the join, and run down the outside of the oil cooler.

Now my question is.... is this a common failure of the oil cooler gasket? or does it just need tightening up? or is there a more likely cause and I am jumping to conclusions?

MHT

the usual leak from that point is an oil leak, the oil pressure is a lot higher than the pressure in the cooling system. Having said that, it is quite possible for coolant to leak past that gasket. Tightening it probably will have no effect on the leak, there is a silicone rubber gasket between the block and housing that fits into a groove in the edge of the housing, over time the gasket conforms to the groove and looses the tension that makes the seal. What sort of oil pressure problem does your friend's 951 have?

RennBod

I think I need to get something worked out here.

Inside the oil cooler, there is a small radiator type arrangement, the bit I need to straighten out is.. is this radiator filled with oil with coolant surrounding it, or is it filled with coolant with oil surrounding it in the housing.

I had assumed that it was coolant in the housing, and the small radiator/heat exchanger inside was what had the oil in it. Or am I wrong?

or, if I am right, is there an oil passageway there thats close to the outside.

Its just that I am also trying to track down an oil leak as well from that area.. I could only see coolant slowly beading up there (almost like the joint between the housing and the block was sweating) but I am trying to figure out where the oil is comming from.

If it helps at all, I changed my water pump, belts, tensioners, rollers, radial oil seals and o-rings on the front of the engine about a month ago. At first I thought that maybe I had screwed up the water pump install, so expected to find that the coolant loss was a bad gasket on the pump, but having seen what I have seen tonight, I believe its comming from the oil cooler.. having said that, if the oil cooler works the opposite way to how I thought (oil in the outer housing, coolant in the middle) then I cant understand where the coolant could be comming from.

If I go ahead and reseal the cooler, how long should it take me? is it just as easy as it looks on

https://rennlist.com/techarticles/heatexchanger.htm ???

HELP!

RennBod

The problem with the 951 has been listed on another thread.. but basicly, on cold start it has no oil pressure (or at least between 0 and 1 bar) for about the first 5 to 30 seconds (30 seconds feels like a lifetime when you have no oil pressure!)

As soon as it gets oil pressure, it seems to be A-OK, about 5 bar when cold, about 2.5 to 3 bar at idle when hot.

I did think when he called earlier today that it was just his oil pressure sender, but on seeing it first hand, until it gets oil pressure it sounds like a bag of nails (cam followers rattling, many rattles, like a bag of nails)

It almost seems like the oil pump is loosing its prime when the engine has been shut off for a while.

Scuba Steve

I fixed this exact problem last weekend on my car. The rubber part of the seal between the oil cooler housing and the block had gone bad. All other seals were ok, but I went ahead and replaced all of them. If you go to the trouble of getting the housing off doing the other seals is nothing and you really should do all of them at once.

It's not bad, just make sure you have a good drop light so you can see in there. You'll also either need to disconnect the exhaust header or use a u-joint for your socket set to get at the top/front housing bolt. It's a dirty job though. Oil comes from the filter, the sending unit, and the pressure relief valve and coolant starts coming out from the housing when you loosen the bolts (probably less of it if you drain the system by disconnecting the hose at the water pump). Then a little more coolant and oil comes out when you remove the housing and cooler. It's easiest to remove them both at the same time. Removing the flat bar that runs from the frame to a suspension rod and the power steering pump helps out a lot. It'll probably take about an afternoon from start to finish.

924martinirossi

Remove the pipe across the head, remove exhaust manifold, take wires off the oill pressure switch and remove sensor, unbolt (4) bolts and remove cooler and replace all the seals. I used a orange based cleaner to flush the block and radiator, to include the tank to rid all traces of oil in the coolant system. I have had to do this on two of my 944s within the last 5 months.

SD Porsche Fan

I noticed that there are two different procedures for this job. Clark's Garage has you remove the header.

Tech Area on the Rennlist home page has a procedure by Kevin Gross & Al Broadfoot that has you remove the right upper sway bar mount and mentions nothing about removing the header.

I'm thinking about doing this next weekend. Can anyone tell me how long it took them and which procedure they used?

Also, did you go with the spec alignment tool or did you use something else?

sm

There's no need to remove your headers. In fact, you don't *need* to remove the oil lines either. I just took off the heat shields, loosened and rotated the sway bar bracket on that side, maybe unfastened the hard p/s line, removed the OPRV, removed the oil filter, removed the 4 bolts to the oil cooler housing, and replaced the seals from above. For the 951, you'll have to muscle the oil "pipe" that fits between the housing cover and block. Do a search under my name in the forums and there are some pics of what I'm talking about.

This is after draining the coolant and oil, of course.

RennBod

Thanks for that guys, I am about to start on it.

Mine is not a turbo, can anyone confirm that I dont have to remove the headers on the NA motor? As I think the oil cooler housing is bulkier on the non turbo, so access may be hampered.

I have my seal kit, looks like it contains...

1. One metal gasket with green rubber seals bonded into it.

2. One black rubber seal (looks like a quarter inch thick off cut of heater hose)

3. Two green o-rings (About 3/4 inch diameter)

4. two aluminium washers (about an inch across with a 3/4 inch hole in them)

5. One white plastic washer, about the size of the two other washers, but thicker

Anyone able to tell me where it all goes, just in case I get mixed up!

thanks guys, you all rule!

RennBod

Ok, two hours have passed... I am almost half way...

I would have been at this point an hour ago, but me being me, I thought that the heat sheild would not come all the way out... So I have been trying to get at the two bolts at the top of the cooler with the heat sheild unbolted, but loosely hanging in there... I have the cuts on my arms to proove it

Anyway... the question is... I seem to remember on my old 944 pre 85.5 car, that it didnt have a heat sheild... Do I REALLY have to put it back?? what will happen if I dont put it back? Will it really be the end of the world?

Any answers to this will be great, as I can see progress being much swifter if I ignore fitting this PITA sheild!!

Also, any advice will be great on what the seals in my previous post are for... I guess I am about to find out, but it would be nice to know of any pitfalls before I dive in and end up having to do this again tomorow!

When I am all done, I will post a proceedure of what I have done and how... just for the archives, because I have found plenty of threads with some of the info, but I think I will post a separate topic mentioning how I did it from start to end. is that reasonable? or will it be seen as a junk post?

924martinirossi

I have a PDF file to email you, check PM then email me.

RennBod

Well its off!!!!!!!

That front top oil cooler is a pain with the headers still connected isnt it!!!

I ended up using a 1/4 inch drive small ratchet with an unusual combination of short bars and socket to get on it from bellow.

Looks like the oil cooler gasket had failed, it seems to be rusty all around the top section, with signs that coolant has been leaking past the rubber seal for some time.

Also the O-rings on the cooler inside do not look to healthy, so I could well have been only a short while away from having the milkshake coolant syndrome!

Anyway, Im done for today... more exiting installments tomorow when I will clean it all up and get it all re-installed (possibly)

But I also need to order a new water pump to heater rail hose, mine does not look so hot, so it may not be running till monday.

Thanks for everyones help so far, you really are all the best!

924martinirossi

That is why I removed the headers first. Also that gave me a chance to put new studs and copper nuts on during the re-install

Scuba Steve

I also had to get creative to remove those upper cooler housing bolts. The rear one wasn't a problem but the front one required a u-joint . Removing the power steering fluid tank, pump, and flat support that bolts to the frame made things much easier.

My gasket was rusty, and from the look of things whoever did the job long ago wasn't very good at getting the original gasket out of the groove in the housing so I got to scrape it out. They also didn't put it all back together very carefully; the black rubber seal had fallen down and was stuck between the cooler and block all those years. That seal and the plastic washer are prone to falling down during reassembly.

I didn't use the special tool and things seem to be ok a week later. I installed the four housing bolts so that they were finger tight and then threaded in the pressure relief valve by hand. When you can thread it in all the way by hand it is adjusted correctly and then you can tighten the housing bolts.

Granite 944

Make sure you read http://www.clarks-garage.com/shop-manual/lube-01.htm , make sure every thing is clean as a whistle, and note: if you have the early style oil cooler (that has not been machined inside), you will not use the white plastic washer. I believe the later/updated cooler housings started around '87, but all these cooler reseal kits have this white spacer in them, which is used on the updated housings only.
I also remove the exhaust headers, when doing this job. The more access to the cooler, the better, easier, the job of this cooler WILL go, IMO.
Unless you want to help to defeat/lessen the purpose of having an oil cooler in the first place, I'd put that sheild back on. Pay close attention to the OPRV, its type, operation, and alignment. Good luck!

I just noticed my reply is kinda late.............HAPPY THANKSGIVING! at least!