86 951 Driver

http://members.rennlist.com/tom86951..._seal_repl.htm

Looks like that is the most complete guide to changing this seal for the 944 Turbo. Besides the stubby 24 MM wrench what are some other helpful tools? I can't seem to fine my u joint extensions so I will need to pick up another set.

Check out the last post. Need some advice.

Darwantae951

I didn't even need a stubby. The biggest PITA for me was getting the damn heat shield off! Do you have a 3 piece OPRV or the updated one piece?

zerMATT951

Yup... Tom's write-ups are great!

86 951 Driver

I haven't torn apart my car just yet. I have no funds to fix it right with my wedding approaching rapidly. Just over 40 days until the big day. Once I dig into it I will know. My car is an early 86 built in Feb. 1986. I would assume the 3 piece one. Is there an advantage to one over the other one?

Darwantae951

3 piece is old. Porsche made a one piece retro-fit valve for the early blocks.

zerMATT951

Yeah... Over $500 from PCNA and nobody is selling used ones for under $100 anymore.

I read up on the subject during my rebuild and found that most opinions were that I'd your 3-piece doesn't stick that they actually work better than the 1-piece. I reinstalled my 3-piece and it's been working fine.

Darwantae951

My inquiry about which OPRV he had was to determine if he needed an alignment tool or not.

As far as three piece OPRVs being better than the one piece units, that's new to me. Please point me to where you read that. I'm not saying either is better than the other, as I don't know. All I'm used to is the one piece, and it has been fine, as well.

jmj951

I also have an 86 and will be doing this job very soon, so I'm interested in finding out more about the tool for the OPRV.

I also plan to replace the headers. If the headers are out of the way, can the housing be pulled out from above, instead of removing all of the power steering accessories and pulling out from below?

86 951 Driver

I am not looking forward to this job, but I figure that I will make the best of it and actual bag bolts up and mark them then also replace the powersteering lines as well as maybe fixing up oil lines as well.

Darwantae951

I didn't try out the top, because I had headers installed. Out the bottom really wasn't that big of a deal. I unbolted the pump, and dropped the rack on the passenger side. If you have the 3-piece OPRV, be sure to buy/borrow the alignment tool so that you don't have the piston bind.

zerMATT951

From Clark's Garage:

"If you have a vehicle that uses an old style three piece relief valve, I recommend NOT replacing the old style valve unless it fails. In my opinion, the old style valve is just as reliable as the new style valve. The newer style valve is also a bit pricey."

I decided to stick with my 3-piece when I was putting my engine back together. I didn't do anything special when putting it back together and it seems to be working just fine... no special tool, I just checked the valve for proper movement before tightening everything down.

For what it's worth, I had housing and 1-piece valve out of my 924S twice and never had an issue during re-assembly, and I didn't use the special tool. I installed the housing & gasket/seal leaving the bolts loose, then slowly inserted the 1-piece valve with some oil on the o-rings. I kept the valve loose and made sure I could remove and install it a few times while I slowly tightened the housing bolts. That procedure made sure that everything was in alignment, but using the actual valve as an alignment tool. I had no issues either time and always had proper oil pressure for the 75k+ miles I put on the car while I had it.

Darwantae951

Not using an alignment tool assumes some risk for binding after reassembly, regardless of past outcomes.

Is Clarks Garage the only reference you have for that? His opinion seems based more around the price of the new unit, over actual functionality. I would prefer an engineering perspective over speculation.

I was actually talking about this last night to a few people, and the overall opinion was this:

The 3-piece OPRV works fine if left alone. Being a piston traveling inside of a bore, it does develop wear paterns with the sleeve inside the block. Repeated disassembly/reassembly can exaggerate wear on the piston, and eventually lead to binding. Most change over to the later style, especially if they routinely pull the housing off (I.E. track car engines with maintenance intervals).

Oh well tho, the OPRV is not what the OP was asking about. If the OP is worried, the tool is ~$40 from Paragon. I'm sure that someone on here can lend it to him tho. Mine has been around the country a few times already!

86 951 Driver

Bump. I'm wanting to acquire tools for this job. It appears the only special tools I might need are a 32 MM oil line wrench and the 24 MM stubby.

Would these wrenches be a bad idea?

http://www.harborfreight.com/15-piec...set-93668.html

pkt1213

Well Jeff, now you can come down and help do my timing belt, water pump, front seals and new head gasket.

Also, congrats on the wedding.

jmj951

I'm in the middle of this job and getting ready to put my housing back on today. I bought tool 9215 for this job, but now I'm not sure I actually needed it. It seems that the special alignment tool is only needed for the one-piece valves, not the three-piece valves. When I removed my housing, the end of my one-piece OPRV was well within the bore. It did not protrude from the block at all. My oil pressure was normal (actually great) before the job, always up to almost 5 bar except when warm and idling, then between 3 and 4 bar. Better than my 996 actually. Maybe what I don't see is that the valve is pushed into the housing at higher pressure - I don't know. Regardless, I'll use the tool since I have it anyway.

I'm doing this job from the topside since I happen to be in the process of changing the headers anyway, and it's far easier than I expected - no special tools needed. No stubby wrenches, no thin wrenches, just a few large adjustable wrenches. Probably helps that the PO did a reseal job about five-six years ago, so the oil cooler lines weren't terribly hard to remove. However, I can easily tell why I have to do it again - he did not clean up the pipe with the two orings between the block and the housing, and he didn't replace both o-rings on it. I think he only replaced the housing gasket and one of the two o-rings, because one orange cylinder-shaped o-ring (which was in the housing side of the pipe) just broke apart when I removed it. I'm guessing that little pipe stuck into the housing when he pulled it off, and he didn't realize that it needed to come out. My o-ring replacements are both the green donut style o-rings, very different than the one he didn't replace. Both the pipe and the bore were very dirty and took a lot of scrubbing to clean up.

Now that I've had things apart, I'm really glad I did this job. To be honest, I was borderline on doing it because the oil fill cap hardly ever had any evidence of moisture in the oil, and the coolant reservoir cap would only get a bit milky after a month of driving, I just figured I'd go ahead and do it while I had the exhaust manifolds out. Once I had the housing off, I found out where all of the blown head gasket pieces went! My last HG failure was partially due to rusted out areas of the gasket around the fire ring. Those rusted out pieces, plus the other debris from the gasket, ended up in the oil cooler housing. Now I'm wondering if there are any other areas that have any buildup like this... Bottom line, I've learned that if you've had a nasty, rusty head gasket failure, it's a very good idea to clean out the oil cooler housing - and an easy job since the exhaust manifolds are off when replacing the HG anyway.