924Board.org

[jpdorfer]

Peter

I too have just recently completed a total rebuild with zero previous experience. I had some help assembling the rods pistons crank. You are right, it is not an easy process. I took pictures of the engine coming out and once on a hoist at all angles. It was invaluable. Also with out baggies I would have been in a world of hurt. I used the gallon sized and sandwhich size ziplocks and used 3 x 5 cards for notes placed in each baggy as to what it was. I finished with only one part left over!!! Finally figured out what that was....The cast aluminum fuel distributor shield.

I do have an oil leak at the turbo cooling line that I am going to have to deal with.

JayD

[Peter]

Glad to hear of another first-time rebuild.
Yeah, those sandwich bags are indispensable. I used self-adhesive computer address labels instead of index cards. I also used glass spaghetti-sauce bottles to help store other small parts and as a parts washer.
As for the oil return line, I replaced mine. Get 3/4 ID silicon or high temp hose and two hose clamps. You could see the blue line in one of my pictures.
I am still putting mine back mine back together, but will continue to post pics as I go along.
Once again, Congrats!

[Lizard]

congrats on the rebuilt. I have done a few and never labeled anything or took any photos but I have a photographic memory and remember where things go very well, and they always run too

[Peter]

Just another update:
Recently finished rebuilding the wastegate. I took apart two units to make one good one. The first unit had corroded studs, so I decided to rebuild it. Well, only 2 out of the 8 studs came out without breaking. Arrrggghhh!!! So, I took out the trusty Cobalt drill bits and drilled out he remaining 6 studs. What a mess. The studs are grade 8.8 iron/alloy composite. Hard as nails to drill out. I would have taken it to the machine shop if I knew it would have been so difficult. On the other hand, the machine shop charged me $20.00 to drill out one broken stud on the turbocharger. Not wanting to retread the wastegate holes, I took a part the other wastegate I had. Spare parts: you never know when you will need them, but when you do, they are a lifesaver.
The other wastegate came apart without anything breaking. The rubber boot was fine so I reused it, while the spring from the first unit seemed better, so I reused that one. I used all new 8.8 grade studs and lock nuts: in case I need to work on this in the future I don't won't to kill myself. I also attached a banjo bolt (from the first unit) to the top of the wastegate to use it as a variable boost controller as per John H's instructions.
Just received my $100 off coupon for being a member of CVR PCA, which had the largest increase in membership of the PCA regions. So I can now buy new turbo & wastegate exhaust gaskets. I actually thought about making my own gaskets out of a thin sheet of sheet metal or aluminum. The gaskets are made of two thin sheets of metal sandwiched around a composite material (probably asbestos?) Anyone ever make their own gaskets?
Here is a pic of the completed wastegate.

[Fast924Turbo]

Nice job on the heat sync where the 'valve' opens and closes. I used Rust Checks 'Rust Converter' to give mine the same finish. Is that what you used, or is that some kind of heat proof paint?

[Peter]

No, I just used a wire wheel to clean the whole unit. I tried Por-15 rust "converter, remover, sealer" or whatever it is supposed to do on some other parts and was disappointed with the results. Maybe I applied it incorrectly? Let me know how you like the Rust Checks Rust Converter product.
Now, I usually just wire wheel rusty parts until they are clean then apply some enamel paint. One thing I may do in the future (read: should have thought of this earlier) is give the "heat sink" part of the wastegate to the machine shop along with the block and have them hot tank all the parts together. Shouldn't cost anything extra and because it is iron it should not be damaged.

[Peter]

Update: Oil Cooler Installation

Just about completed installing a Volvo truck oil cooler to my Audi truck engine . I wanted more cooling capacity than the stock 931 cooler. Initially, I thought about installing two 931 coolers in parallel (or is that in series ?). One cooler would go in the stock location in the front passenger side, and the other would go right across in the front driver side, where the horns are currently mounted. I nixed that idea when I decided to mount the turbo intercooler in the stock oil cooler / windshield washer location.

The first pic is of the Volvo intercooler. It is a 4-pass, tube finned cooler with 1/2 NPT(female) fittings and 5/8 ID tubes. More than enough cooling for me.


The second pic is of my oil temperature sender mounted to a "T" fitting with hose barb ends. I wonder how long it will remain shiny & clean?


The third pic is of the mounting holes for the cooler. The "red paint" is primer; don't want any rust to begin forming on the freshly cut sheet metal. I sanded the sharp edges with a grinding stone mounted on my air die-grinder. The hole on the left is for the oil lines, with a mounting-bolt hole to its right. The hole in the middle is for exhaust air, with the holes on the right are mounting-bolt holes. Note that there is one exhaust hole in the center. This is even unnecessary as the fresh air at high pressure will enter via the front cutout on the bumper(see 5th pic) and through the four vent holes (vents to be installed). Exhaust air will pass down and under the car as it is at lower pressure than the front moving air.


The fourth pic is of the mounted oil cooler.


The fifth pic is of the template I made before I cut the bumper. I cut a rectangular hole in the bumper and covered it with mess wire to prevent debris from damaging the cooler (completed pic to follow next week). I will be mounting the license plate via an "L" bracket to the right-most part of the bumper, almost in line with the driver.


Sixth pic is of the lines in the engine compartment. Hot oil exits engine via bottom line, travels through temp sender to bottom of cooler. Cooled oil returns to engine via top line.

[Matias]

What kind of hoses are those?? you just put it with clamp`s over the oem copper pipes? Mines are still the original, and they don`t look good at all.

[-nick]

that's a good looking install, but what happens if you get into even a minor front end fender bender? is there clearance for the cooler if the bumper is collapsed all the way on the bumber shocks? and did you cut out all the sheet metal behind the cooler so air can flow through it?

-nick

[Lizard]

[Peter]

Matias,
I used 5/8 inch ID oil/ gas hose, temp range up to 300 Fahrenheit, purchased from www.pegasusautoracing.com (in WI, USA). Being in Argentina, I suggest you buy any high temperature rated rubber hose that can handle petroleum products. You should be able to find metric hose that is the factory size. Just a note, I used similar rubber hose & hose clamps on my 924 fuel lines and have had not problems for over 3 years.

Guys,
I knew somebody would ask me this question. First, the bumper is very strong. It's about 1/4 thick aluminum and I had to use a sawzall to cut it. Very difficult. Second, the bumper shocks are also very strong: try pushing one in. But, if an accident damages the cooler, I will use a 5/8 male-to-male barb fitting to connect both rubber lines together, thereby bypassing the cooler and allowing me to operate the car. On low boost, or none at all, the engine can go without an oil cooler, as exemplified by the 924 cars that are tracked or street-driven hard without a cooler. However, if an accident damages me, the heck with the car, medivac me to the closest trauma center!!!!

Just a side note on the bumpers. There is some false info going around this list that these bumpers are only rated for a 5mph crash. This is wrong! Briefly, when Porsche was designing the 924, they looked to the US & other countries to determine compliance with local laws. The 1960s & 1970s in the US was a very turbulent time for social & political changes. There were various civil rights & consumer movements, and a general distrust of big business and government. For example, the hippie and peace movements, Nixon's impeachment, the rise of consumer advocates such as Ralph Nader, etc and of course the Ford Pinot Cases. For our overseas friends, the Ford Pinto cases were lawsuits filed by burn victims and their families against Ford for manufacturing a faulty product, the Ford Pinto automobile, that exploded upon rear impact burning to death its occupants and the occupants of the other cars involved. The icing on the cake was when internal Ford memorandum were made public showing that Ford made a conscious decision that it would be cheaper for Ford to keep the Pinto as it was designed and pay damages to persons burned by the explosions rather than to spend $1.00 US per car to retro fit the gas thanks with a rubber baffle between the suspension bolts and the gas tank (sounds similar to what is currently going on with the Crown Victoria ). Porsche believed that US safety regulations would be greatly strengthened, especially with the growing consumer movements, and so Porsche designed the 924 to meet or exceed any reasonable new regulations. Remember that Porsche is a very small company and cannot easily change with the times, rather it must anticipate and change beforehand. Also remember how important the 924 was to Porsche: it saved Porsche from going under. However, you don't have to look farther than this list to see some of the 924s that have been involved in impacts and are still drivable.

As for room for the cooler, the bumper is shaped like a "C", in that the inside has a large hollow section. The cooler has about 4 inches clearance, in that even if the bumper is hit and the bumper shocks collapse, the bumper could make contact with the car and the cooler would be protected in the "C" section. At the most, some of the fins may be bent. But if not, then I use the barb fitting mentioned above. Another plus for the US bumpers .
As for exhaust air, I only made one hole and don't think that was even necessary. I know the topic of "air flow" is debateable, and everyone has an opinion, but after crawling under the car & taking measurements, & wondering about the "whys" & "hows" of Porsche engineering, I cam up with my own conclusions. Based upon my conclusions, air enters the front 4 vents (above the bumper) and the grill (under the bumper). The hole in the front bumper will allow air to enter the cooler directly head-on. The exhaust air will be directed to the back of the cooler by the fins, which preclude any left or right air movement. The exhaust air must then either exit up or down. Because the lower part of the bumper is rounded and longer than the top, air entering the four vents is traveling at greater velocity than air entering the bottom, as such, the oil cooler exhaust air should exit downward. Also, the US bumper is not flush, rather there is a gap, which will also allow air to leave. Some of the exhaust air would be sucked into the lower grill. However, there should not be any noticeable rise in coolant temperature because more air is entering the radiator area. This is supported by my own experiences with my 924 track car that has an oil cooler mounted in front of the radiator, with no noticeable coolant temp increases during clam or aggressive driving.
Anyway, as I said, we all have our opinions .
[/i]

[-nick]

"On low boost, or none at all, the engine can go without an oil cooler, as exemplified by the 924 cars that are tracked or street-driven hard without a cooler. "

i thought all 931's had a cooler? i didn't want to give you a hard time, i just had to bring up the obvious be sure to post some pics of the finished product, i'm curious to see what a big hole in the bumper will look like.

btw- do you make it out to an of the CVR a/x's i don't think i've seen you. i've been trying to find the time to get out to the Glen for a while now...

-nick

[Peter]

Hi Nick,
No CVR Ax's yet. However, plenty of CVR DE's at Lime Rock. Next time I go, I will post to the list plenty of time in advance, so that maybe some of us Northeastern 924 guy/girls can get together. The Glen was the first track I ran at DE. Nice track but too big for a 924; Lime Rock in my opinion is perfect for the 924.
As to the oil cooler quote. Yes 931 cars come with an oil cooler --stop giving me a hard time Nick What I meant was that if my oil cooler is damaged and I reroute the oil lines to BYPASS the cooler, obviously the oil will not get cooled. Thus, I will be running my 931 without an oil cooler for all practical purposes (The cooler will still be on the car but damaged. So I will bypass it so that engine oil will not shoot through any holes). Is running a 931 without an oil cooler bad? Sure if you run the 931 at high boost. But at low or no boost, the 931 should not have oil temperatures anywhere near as high as a 924 running hard, and 924 cars do not have an oil cooler. So in conclusion, incase of damage to the oil cooler, I bypass the cooler with a male-to-male barb fitting, causing the oil to leave the engine via bottom line and make a "U" turn and enter the engine via the top line.
I hope this clears up any confusion. I will post pics of the final installation.

[Peter]

BTW, my avatar is a pic of me at Lime Rock, the last right-hand turn before the downhill.

[Peter]

Here is a pic of the completed installation. I think it looks good (but of course I would say that ).