944 coolant leak....

[galis]

I found some (wet but not a lot) coolant on the top side of my 84 944 engine today. It has consumed about 2 quarts in the last 2000 miles. Not sure if it was coming from what looked like a corroded temp gauge or what looks like the head gasket. Are either of these common spots for a leak? I'm hoping it's the temp gauge or re-torque the head to fix. Having just replaced timing, et al belts, I'm not excited about a head gasket replacement. How involved is that? What other preventive maintenance should I think about if the head is coming off?

---George

[harnishclan]

When you say two quarts-assuming you mean coolant.

Did you check bleed screw to make sure it is tight?

What does coolant look like in overflow tank? Is there oil in it?
Check dipstick, is there any evidence of coolant in oil?
Is there any white smoke through the exhaust?

Head job starts with taking off the timing/balance shaft belts again and going from there!

[galis]

When you say two quarts-assuming you mean coolant.

Yes more of a big seep than a leak....

Did you check bleed screw to make sure it is tight?

Um, no. I guess that would be under the radiator? Haven't seen anything on the ground just some coolant on the topside of engine.

What does coolant look like in overflow tank? Is there oil in it?
Check dipstick, is there any evidence of coolant in oil?
Is there any white smoke through the exhaust?

The coolant in the overflow looks new, as does the coolant that has leaked out. The oil on the dipstick looks a bit browner after the AX but I don't think it's from the coolant. The engine is running perfect with no smoke and normal smells from the exhaust.

Head job starts with taking off the timing/balance shaft belts again and going from there!

If I'm lucky it's all coming from that corroded temp sensor.
If I do end up pulling off the head would it be silly to just just replace the gasket? What preventive maintenance should I be thinking about as well?

-g

[Dan Chambers]

Did you replace the water pump when you did the belts (best time to do it)? Sometimes when you replace the timing belt without replacing the water pump the stress of the new belt tension on the old waterpump bearing will cause a waterpump bearing failure (ask me how I know ).

One way to check your waterpump for issues is to listen to the pump housing when you first start the engine ... cold start. Take a long screwdriver and place the blade side on the top of the waterpump housing and the handle-in-hand on your ear. Do you hear any little clickity-clattery noises eminating from the water pump? If so ... TROUBLE! You'll have to pull everything out and replace the water pump. Then replace the front-engine seals (while you're in there), the rollers where needed, and re-replace the newly purchased belts if they haven't been fouled by coolant. You should really consider doing this if you plan to track the car. Iknow, I know: it's a PITA, but it beats getting stranded with a blown waterpump (again ... ask me how I know ... part II ).

It's common for a pin-hole leak to develop as the head-gasket goes, leaking coolant into the area just under the intake manifold where it ponds on the head/case and then evaporates ... causing odor. Got odor?

Brian is on it for bleeder bolt, and other stuff. That's all relevent stuff.

You can have the cooling system pressure-tested by a competent garage like Black Forest, Dieter's, Mireage. They'll pressurize the cooling system and check for leak-down. If the leak-down is great, there's a head-gasket in your future. Might as well check the valves and consider a top-end job while the head is off, IMHO.

Hope that helps. Good luck.

[galis]

It's common for a pin-hole leak to develop as the head-gasket goes, leaking coolant into the area just under the intake manifold where it ponds on the head/case and then evaporates ... causing odor. Got odor?

No odor yet.... surprises me given about of coolant visible, must be a cooler part of the engine (below the intake).

I didn't want to be too optimistic, but I got a better look at that temp sending unit while at black forest today. It looks really bad, heavy corrosion. I just learned that is a good indication of a leak point and an easy fix, so will start there....

-g

[Dan Chambers]

I didn't want to be too optimistic, but I got a better look at that temp sending unit while at black forest today. It looks really bad, heavy corrosion. I just learned that is a good indication of a leak point and an easy fix, so will start there....

-g

That could be very good news. If it's a bad temp sender, and replacement is fast and cheap ... you've dodged a bullet. BTW: don't forget to bleed the air at operating temp once you're done with repairs. I bled my system two and three times just to be sure there was no air-bubble causing trouble in the system. I'm sure the guys at Black Forest will be thorough, but check it yourself just to be on the certain side of things.

Good luck, and hope to see you at the driving events.

[galis]

That could be very good news. If it's a bad temp sender, and replacement is fast and cheap ... you've dodged a bullet. BTW: don't forget to bleed the air at operating temp once you're done with repairs. I bled my system two and three times just to be sure there was no air-bubble causing trouble in the system. I'm sure the guys at Black Forest will be thorough, but check it yourself just to be on the certain side of things.

expected a slippery slope, but nobody told me about dodging bullets!

the leak does seem all fixed with the new sending unit, but short of refilling the reservoir, how would I bleed the system?

-g

[Dan Chambers]

....the leak does seem all fixed with the new sending unit, but short of refilling the reservoir, how would I bleed the system?-g

To bleed the system you'll need:

Paper Towels
Wrenches
Mechanic's gloves
Spray bottle with Distilled water
ground cover/drip pan/fluid catch system

To bleed the system:

Locate the radiator hose that enters the head, next to the cam housing and intake manifold and up/behind the distributor cap. On top of the hose flange that the hose is fitted on is a 12M or 13M bleeder bolt. Be sure the wrench you're using fits the bolt properly. Place the drip/fluid catching system under the front of the car. don't let the coolant/water run onto the ground and into the street. Surfers don't like the taste of ethylene glycol, and it's now a crime to knowingly discharge fluids into the storm-water system. (Note: there are water-narc's everywhere. Be environmentally consciensious.)

Be sure there is plenty of coolant/distilled water in the reservoir. Start the engine and let it warm up to operating temperature; I wait until the fans cycle on once.

Carefully stuff the paper towels around the radiator hose and cam housing, and under the intake manifold to absorb coolant as it's being bled. With the engine running, loosen the bleeder bolt slowly until coolant/air (hopefully) squirts out. Use a towel over the bolt if it's squirting aggressively. Tap the hose and hose flange (where the bolt lives) to ensure any trapped air is dislodged. Close the bleeder bolt.

I used to open the bolt for about 5 to 8 seconds to bleed the system. That may not seem like much time, but when hot fluid is squirting/spritzing everywhere, five seconds is an eternity! The mechanic's gloves will help prevent any hot fluid from irritating your hands. I also have used Nitrile or Playtex gloves. The idea is to protect your hands from 180-degree fluid. Try not to let the fluid get into or behind the timing/balance shaft belt cover. Timing belts don't like ethylene glycol, either (I think they go surfing when you park the car ).

If you think you have more air in the system, open the bleeder bolt for another 5 seconds. Check the reservoir. Still plenty of fluid in it? Good. As long as you have fluid in the reservoir, you can repeat the bleeding process. No fluid? STOP! Wait for the engine to cool down, and add more distilled water to the reservoir (never use tap water in your coolant system). Do not open the reservoir cap when the engine is hot. It is pressurized!

Turn off the engine, remove any wet paper towels, take the spray bottle with distilled water and clean off everything nice and dry. You want to make sure all the discharged coolant is cleaned up to reduce odors when driving, and prevent any long-term corrosion from old coolant ponding around the head and cam housing.

Be sure the bleeder bolt is tight.

You're done. Have a beer and relish the peace of mind only a shade-tree DIY mechanic can have.

Good luck!

[harnishclan]

Did Black Forest replace the sensor or sell you one?

If they replaced it, you are done. The only steps and tools you need are drivers license, insurance, registration, and keys. If you replaced the sensor, I would take it to a shop and have them check your work. 944's can overheat pretty easily if the bleeding is not done and overheats often result in expensive repair bills.

[galis]

Yes, they seem to know what they are doing. nevertheless I am a mechanic at heart, so any guidance in the black arts is well appreciated.

Me thinks my failed temp sensor introduced air into the system in the same place it was leaking, with the heating/cooling cycles. If the 3 marks are 25, 50 and 75% of the operating range it was reaching 30% before where as now it doesn't get over 10% on the street.

Dan, much appreciated breakdown of care and concerns.

Next step, a darty performance alignment and no more understeer!

-g

[Jad]

Most likely they just put a cooler thermostat/temp sensor in. There are a lot available for the car and tracked cars need cool ones.

It is nice when it is a relatively cheap fix.