924Board.org

cookcj

All right ya'll here's the restoration quandry of the week. In the restoration of my 1980 Porsche 924; I have repalced the alternator and it's associated belt, the battery, and the radiator resevoir. However, my 924 overheats in approx. 10-15 mins after start-up while in park. Noting that this may possibly indicate a 'dead' thermostat, I; like any other kid from Florida who is used to taking out their thermostat in the summer; simply allowed the engine to cool and removed the thermostat (and reconnected all the piping). When I re-started the car, it over heated in apporx 20 mins. Is there a way to determine if my water pump is not pumping enough (water moves when the engine is running { even before it gets hot since I removed the thermostat }) or if my radiator is blocked and thereby reducing the surface area available for cooling? And finally, which do ya'll recommended I replace first, the radiator or the water pump?

tj924 · Posted: Mon Jul 25, 2005 8:52 am Post subject:

OK, firstly put your location in your profile so we know where you are. Second, add your vehicle type to your signature for future posts. Both of these will help others to help you.

In terms of your poll, start with neither! Replace the thermostat with a new, lower temp one as it is there for a reason. Is your radiator fan working properly? Mine kicks in when the temp hits about 1/2 way & I don't have a lower temp thermostat.

Check the waterpump for leaks out of the weep hole on the front just under the pulley. If there are none check if there is any play in the shaft by trying to wriggle it up & down. If it is leaking or there is play in the shaft, replace it.

If your waterpump is OK & you have a new thermostat & you still have the problem, pull the radiator & have it tested.

Also, get yourself a Haynes manual if you don't already have one. Make sure it isn't the older edition. Should have a greenish cover rather than an orange/red one. This stuff is covered in the Haynes.
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TJ
Silver '82 924 NA 5-Speed Manual

tj924 · Posted: Mon Jul 25, 2005 8:57 am Post subject:

Oh, and welcome to the board!
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TJ
Silver '82 924 NA 5-Speed Manual

augidog · Joined: 03 Mar 2003 Posts: 1360 Location: New Jersey

Put your thermostat back in!!! We looked at removing it in the past. The piping configuration will not allow it to operate properly with it removed.
Your probally not getting enough flow with it out.
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1978 924 95 mile daily driver.
Audi TB/POR174M/High Flow Cat/2.25" exhaust
I knew that positive thinking thing wouldn't work.

Smoothie · Posted: Mon Jul 25, 2005 9:31 am Post subject:

I agree. Your whole problem is probably the thermostat. The old one was probably stuck closed, then you only saw a slight improvement with it removed. You should see it improve much more with a new and correct 924 thermostat in place (it should have an extra disc at the bottom - this causes all the coolant exiting the head, to flow through the radiator when the thermostat opens). Without the right thermostat, most of the flow goes right from the head to the pump and back into the engine without going through the radiator.
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"..it's made in Germany. You know the Germans always make good stuff."

'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

cookcj

(1) How does removing a device that restricts liquid flow through a heat exchanger reduce the heat removal charactoristics of the system? It seems to me that by sending maximum flow though the heat exchanger would result in the maximum amount of cooling. (2) I have noted other members talking about replacing the radiator in their vehicle with a 944/928 radiator and how it requires manufacture of speical brackets. Does anyone know anything about this? (3) If the pump is bad, how much should I expect to realistically pay for a replacement? (4) Is there anyway to install a manual 'fan on' over-ride switch? (Between the thermocouple and the fan relay maybe) (5) What's up with the whole warm/hot - restart switch thing I keep hearing about? and finally (6) Why is my 924 hard to restart when the engine is warm?

Oh yeah, thanks for the warm welcome to the group. I'm orginally from Orlando, Florida but the US DoN has me stationed in Maine at the Portsmouth Naval Shipyard
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1980 924 N/A Automatic w/ Factory Air
(First Porsche and first European Auto Rebuild)

D Hook · Joined: 02 Nov 2002 Posts: 3158 Location: Omaha, NE

Per #1--Due to the way the cooling system is designed, it's actually detrimental to remove the thermostat. If you don't have a Haynes yet, you'll have to take the word of the board members who reply. I think it's covered in the FAQs maybe.

I don't think you'd have to replace the pump unless it's leaking.

Do you know where the car has spent the last couple years? Was it in Florida or up in the East where you are now? That may make a difference in how the cooling system was maintained.

I've put a lower temp thermostat in and a lower temp fan thermostat so the fans will turn on sooner than stock. I've also had the radiator cleaned out and rebuilt about 15 years ago. My gauge would go above 1/2 way before the fans would kick on. Then I cleaned my grounds under the dash and cleaned the plug that goes into the back of the gauge. The needle doesn't go above the middle line anymore. Fans kick on at about the first mark. Temp stays right at the first mark on the highway and just above in the city.

You may have to wait and get the Haynes and read it over. I'm just telling you what worked for me. YMMV.
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'80 924 n/a SOLD

Smoothie

cookcj

Charlane · Joined: 25 Jul 2005 Posts: 50 Location: San Antonio, TX

NO! It's not all about the thermostat! This happened to me and some SOB tried to sell me a waterpump job for $500 but I took the car home. What I did was take a $3 tube of die-electric grease and a small paintbrush and brushed on this conductive gel on all of the electrical fan components and electrical components relative to the pumps and cooling. Don't stop there either! I went over all of the spark plugs, coil, all ground, battery terminals, etc. My baby fires right up with just barely a tap at the key. I tightened the belt at the alternator/water pump and used a little belt dressing to keep it nice and resilient. After you have done all of this, test your battery voltage! If you are pulling less than 13 volts, consider increasing your throttle to increase the action from your alternator which translates into your electrical cooling!

One last thing. On the side of the expansion tank is a water hose. Make sure this guy is connected and if not, do not let it drip down because it will drain your coolant! At the minimum, make sure that this hose is placed upward so that any water momentum is reduced and so is the reduction in the level of your expansion tank. If you think you are losing coolant, just place a piece of cardboard underneath and turn over the car for a few minutes and pull it out. If it's clean, you have no leaks. My cardboard was dry, dry, dry.

I found this out all by accident and with my meter and a lot of attitude. My car runs cool now! SMASHING!

Charlane
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Electra is Here......

One 1980 924 Turbo
One 1990 KZ1000P (CHPS) Motorcycle
One 1984 244 Turbo Volvo (B21FT) (I installed this engine myself)
One 1977 240D Mercedes Benz
One 1970 Chevy Impala

Rasta Monsta · Joined: 12 Jul 2006 Posts: 11733 Location: PacNW

-nick · Joined: 16 Nov 2002 Posts: 2699 Location: Cambridge, MA

In addition to replacing the t-stat, make sure you have a solid ground from the battery neg to the body, and from the body to the engine. I left my battery-body earth loose and my temp gauge was reading at the 3/4 + mark when it was actually at a perfect 180F (around the 1/4 mark on the gauge). Tightened the earth, and it read correctly.

ps- contrary to Charlane's notes, the coolant system is sealed. Leaving the small reservoir-to-radiator hose off is like leaving the reservoir cap off. The system won't build pressure.

Slam · Posted: Tue Jul 18, 2006 8:02 am Post subject:

A couple of quick checks: get a stethoscope and listen to the water pump with then engine running. If it's on its way out, you'll hear it. Plus, there's a weep hole on the underside of it. Check there for coolant seepage. The pump is easy to replace if it is dying.

If the rad doesn't leak, give it a good flush. It's easy to take out and any rad shop can pressure test it for you if you want to go that route.

I'd agree about the thermostat issue, and add one thing. Make sure the rad cap is OEM. Using the OEM rad cap can save lots of chasing when it comes to diagnosing overheating.
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'88 944 Auto - may or may not resurrect

D Hook · Joined: 02 Nov 2002 Posts: 3158 Location: Omaha, NE

WOW! This thread is a year old. Never heard from the OP if he solved the problem. Can only assume he did.
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'80 924 n/a SOLD

seanski44 · Joined: 13 Mar 2006 Posts: 532 Location: Nottingham UK