924Board.org

[KDJones2000]

Well we just finished up the Chumpcar 24 hour race in Buttonwillow. We had our 1978 924 out there.

Previously we had run a 24 hours race at Willow Springs / Streets track in 2011, then about 4 hours and then 15 hours at Autoclub Speedway. The 2 times that we didn't blow up we finished mid-pack, which is about as we expected for the Toofah.

Well this race ended up being much different than the previous ones. I am wondering how many others have experienced similar issues with their 924's. Here is a diary of our race:

Team Toofah #124 just got home from our 9+ hour tow back from Buttonwillow. Overall had a good time, but this was our "Murphy's Law" race. Every pit stop seemed to cause something to fail, simply by adding gasoline into the fuel tank. Here is a probably incomplete list of things that went awry:

1) 2-3 hours into the race our driver reports hearing a loud "clunk", and then the Alt light goes on. He pulls into the pits and we discover that it's not the belt that has snapped, but the drive pulley on the harmonic balancer. This thing just fatigued away and came clean off around the 6 bolts attaching it to the crank. Being a well-prepared team (sort of), we had a spare drive pulley and belt, so on it goes and out with the next driver.

2) Two laps into his stint and he reports that the car has stalled. Tow time back to the cold pits to find out that the fuel pump has quit. Well we only have an old used spare pump, which we find out doesn't work (Remember the "sort of"?), and checks at stores basically have them laughing at us. "Do you have an electrical fuel pump for a mechanically fuel injected 30 year old foreign car in stock?". Well it turns out that miracles actually do happen: We were able to unstick the fuel pump by rocking it back and forth by changing polarity, the first time that has worked for me EVER. Back in it goes, and back out goes our driver.

3) Driver now is at the end of his stint, ready to come into pit lane when the Daihatsu carnage occurs. Red flag, all cars stopped on the track. Since this POS Porsche 924 is notoriously difficult to start up, especially when hot, we tell him to try to keep it running. He then reports that the car is overheating while stopped on the track. He shuts it down, and shortly afterwards all cars get to go into the pits. Amazingly it starts right up. The car comes into the hot pits, stops and promptly starts puking its coolant guts all over pit row. After the red flag lifts we find out that the wires for the cooling fan have come out. In they go but there was no way to replace the lost coolant. The next driver goes in and out he goes. Things are looking good finally!

4) Or not. 20 minutes into his stint and he reports high temperatures. Into the cold pits for some surgery with the fan wiring. Out again and it's "drive to the temperature gauge" time, losing about 5-10s per lap to keep it only halfway into the red. He finishes up his stint, fuel and a new driver go in. This is what endurance racing is all about, right? Looks like things may be settling down...

5) ...and the car stalls at pit out. Car is running terribly, even though it was just running fine. We limp it back to the cold pits and try to figure out what the heck is going on. After some major adjustment to the CIS settings we get the car going well enough to put it on the track again. Into the dusk we go, with the pitch blackness, dust and lousy 55W halogen lights we have. Our driver had run at night before, but not in conditions like this. He was basically scared sh*tless out there, what with all of the dust, offs and all that. We found out later that the previous night racing was at TWS (?), where the entire track was basically well lit - not like Buttonwillow at all. Well he survives to tell the tale, and hands the car off to our next driver - more fuel and time to go!

6) And the alternator light goes on, after starting the car in pit lane. We tell him to go out anyway, and I think that he almost saw God - driving on a dusty, pitch black track with what turns out to be dying, lousy headlights. He makes it like 3 laps around before the car completely dies. Time for (another) tow into the cold pits. We have another, used alternator that we think is good - let's swap it out and get moving! Replace it, and we find out it doesn't work. Okay, what about swapping voltage regulators? Well, we finally gave up trying to fix it after the 5th reinstall of the various alternator part combinations.

7) But all is not lost, let's just wait for dawn and finish up the race just running the ignition and fuel pump off the battery! Okay, onto the charger it goes and at least we get a decent night's sleep. Morning arrives, and the car starts up fine and off goes our first driver, who proceeds to spin and stall the car on the first lap. Fortunately it starts right up, but who knows how much of the charge was lost. Off he goes and the car seems to be running great, he's making good times and we move from P20 up to P19 by surpassing someone who broke, probably during the night. Driver finishes up his stint, fuel in and new driver.

3 hours to go! Driver heads out and completes 1-1/2 laps and the car just starts losing the top end, feels like a fuel issue. Dead on the track, time for (yet another) tow into the cold pits. We have pretty much come to know the towing crew on a first name basis by this point. Diagnosis is that the battery has finally died. Thank goodness for Optima! Since they were distributing batteries at this event we borrowed a battery off of a team who had picked theirs up and threw that into the car. Car is again running like a champ so off our driver goes, making the FTD for our team, having a very nice 360 spin in the Bus Stop, and overall enjoying himself. And then....

9) The car just dies. Okay, time for a tow back to the pits. The tow crew mention something about a belt hanging down as they hook up. Hmmmm, what is this one about now? Pop open the hood and find out that the idler pulley for the timing belt has self-destructed. Thank goodness this isn't a 944! Slap on our spare idler pulley, retime the engine and out with the next driver. 2 hours to go until the checkered flag - we are GOING TO MAKE IT! This will be a moral victory, at the very least. And then....

10) Bam! Driver reports an alternator light. Okay, that one is easy, just throw in another charged battery. He drives the car into the cold pits, pops the hood and we find the real cause of the alternator light. The SECOND drive pulley has broken away from the harmonic balancer, taking the belt with it. Okay, we do not have another drive pulley, so this was the end.

From what we can tell so far we think that the water pump that we replaced two nights before the race with a remanufactured one has a bent shaft, which caused both of the pulleys to fail. I gave Cathy the remaining part of one of the pulleys to have as a souvenir.

We also are pretty sure that we have some sediment in the bottom of our fuel tank, and the inline filter we put just before the fuel pump is just not good enough. We converted our fueling jugs over to the "Bill Strong" type, so that we were dumping 5 gallons into the tank in about a minute, and this must have stirred up sediment that we hadn't had to worry about before. Lesson learned.

One of the cool things was being able to keep track of the car from the pits with Wifilapper. Having a second set of eyes on the gauges helped make sure that we didn't blow up the car, at least in inadvertently.



By far the most trying race Team Toofah has encountered, but it was rewarding in its own way. We also helped out the Thundercocks with their brake caliper bolts and brake line, so at least some of our car made P4!
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1987 924S SPEC car
Team Toofah Racing
1988 944 Turbo S

[morghen]

_________________
Supercharger and EFI kits
https://www.the924.com

[tyfighter123]

Wow great write up, sounds like a lot of fun! When is your next race?
_________________
Porsche 924 1977 N/A
Mustang GT/CS 2007
Porsche 924S 1987 (parts car)(cut up and recycled)
Porsche 911S 1976
Porsche 931 1980
Porsche 931 1980 (parts car)

[924RACR]

Very nice, good job.

I'd take a close look at the alternator mounts - they often can cause problems due to the rubber rotting out. Either replace with new, or consider homemade delrin or similar mounts...

Obviously, if those are going, the alternator won't line up properly with the other pulleys, so you'll have a hard time with the belts too... unless you've already attended to this?

HTH...

Oh, yeah, and I'd do a head gasket on that puppy as a matter of prevention; after all that overheating, odds are good that it's popped.
_________________
Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype

[KDJones2000]

The alternator rubber mounts are actually in decent shape. Even if they were worn, I don't see how that would cause such a high amplitude wave function to cause the drive pulley to fail after only about 4 hours.

We were shifting at 5000 to 5500 RPM, so we were killing the engine either.

Well our plans were to ditch the Toofah after this 24 hour race and get a 944 up and running for the next race, but since we still have 3 untouched tires, plus 5 others that are still in decent shape, we are going to run it one more time.

Our drivers want to actually PASS someone else...

The oil pressure in this engine is a bit questionable, as we are getting 0.5-2 on the pressure gauge when hot (and revving, not at idle). Looking in the oil fill cap you can still see lots of oil coming out of the cam drip manifold, but the gauges are telling us to watch out.

This problem existed before this race, but at no time did the car show any signs of oil starvation. Our plan now is to drive it until it dies.

Anyone have an extra (or 2) drive pulley they will send our way?

Cheers, Keith
_________________
1987 924S SPEC car
Team Toofah Racing
1988 944 Turbo S

[Grenadiers]

I have a cast iron one you can have. Not sure what toofah it's from, but it's 924, has the lower cam belt pulley attached. Just the trip down! Here's a pic of it compared to the 931 pulley. The outer pulley on the 931 drives the alternator. That is not available on this one, not sure if this is correct for n/a's.

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'83 944 Track car.
'88 924S Track car.
'89 944 Turbo
2004 Winnebago Vectra monster RV
2012 Jeep Wrangler
2014 Kia Soul
2001 Ford F350 powerstroke

[KDJones2000]

The one on the engine looks more like what we had, but that small groove is not being used anymore.

Sounds great, Dave!

Our next race isn't until November, so no rush for this at all.

Now I just need one more
_________________
1987 924S SPEC car
Team Toofah Racing
1988 944 Turbo S

[Grenadiers]

Ok, I can put it in my 'take to Arizona' box on the shelf if you like. Arriving mid-October I reckon. Want to flog the CGT car at Arroyo Seco with the S. Arizona PCA group again the third weekend in October. dave.
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'83 944 Track car.
'88 924S Track car.
'89 944 Turbo
2004 Winnebago Vectra monster RV
2012 Jeep Wrangler
2014 Kia Soul
2001 Ford F350 powerstroke

[KDJones2000]

I just matched up our Alt and WP pulleys to a 2-groove pulley like the one in your picture and found out that they are aligned with the outermost groove.

These 2 groove pulleys won't work for our car, unfortunately. I never thought that I would have this hard of a time finding one of these...
_________________
1987 924S SPEC car
Team Toofah Racing
1988 944 Turbo S

[Rasta Monsta]

Running this again next year? Please keep me in mind.
_________________
Toofah King Bad

• WeiBe (1987 924S 2.5t) - 931 S3

[Grenadiers]

[KDJones2000]

You actually only need to remove the 6 allen headed bolts to get it off. It slips off of the timing belt drive gear without having to remove that main bolt.

Let me know if you are bringing it, as it will change my strategy to solve this issue. Actually, can you bring both the 2 and 3 belt pulleys, just in case?
_________________
1987 924S SPEC car
Team Toofah Racing
1988 944 Turbo S

[KDJones2000]

[Rasta Monsta]

Well, I know a thing or two about racing a 2.5, so let's keep in touch.
_________________
Toofah King Bad

• WeiBe (1987 924S 2.5t) - 931 S3