Best way to completely bleed the 944 cooling system
 

After successfully using this to helping a buddy during the summer who was having a hard time bleeding his cooling system (running hot / with fluctuating temp gage) I thought I would post it here since I haven't seen it on this site.

The cooling system on some cars can take a long time to bleed, we still had bubbles appearing after 40 minutes of running but eventually they stopped and the car is now running cooler and the temp gage is rock solid. Finding the 8mm grease fitting was the hardest part. The greasefitting may have some residue on it after removing the check valve so it is advised that you use some brake cleaner to clean out, you don't want geasy coolant running back into the coolant tank.

Requires:

8MM grease fitting
4 feet of 1/4 inch clear tubing


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Jaak Lepson re-posted this on the Rennlist site:

An easyest way to bleed the system is use a 8mm grease nipple fitting with the spring and ball bearing removed. Attach a 6 to 8 foot long piece of clear tubing and connect them together with a ty-wrap.


1. Raise the front end of the car.

2. Remove bleed bolt and replace it with the tube/nipple.

3. Place other end of clear hose into the coolant tank.

4. Start engine and turn heater on to full.

5. Run the car until no air bubbles are visable ... hence clear hose!

In some cases the is so much air in the system that it may take up to 45 minutes till air has been removed. If it takes longer .... maybe a HG problem.

6. Replace the Hose/nipple combo with the bolt.

7. Lower car.

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"Best way to completely bleed the 944 cooling system"


I can't believe nobody has said it yet.

Buy yourself a coolant pressure tester. Best thing since animal crackers! ;) Does MORE than just........."bleed" the system!

Stant, is the model I got some time back. NEVER, have I regretted it, EVEN at its cost. Works on most cars too, and it even comes with instructions.

:D

Granite,

at what PSI do you test the 944 system at?
how do you use this tool to bleed the system properly?

Buy the tool. IT will come with instructions, and combined with clark's garage's procedure, you CAN'T go wrong. BEATS the bejesus outta the other methods. Think about it.

Adjust your pressure test pressures depending on the condition/age of your cooling system components.

In other words, if you have old, crappy parts in the car, you sure as hell don't want to stress them more by pumping the pressure up to the maximum pressure of 14.5 psi for the earlies, or the 21.75 psi for the later ones. Stay below this at maybe 10-12 psi. Unless of course, you REALLY wanna know. Ive done it at the max, and I assure you, you WILL find the weak links in the system, so be prepared.

Granite,
if your referring to the stant 12270 it wont pressurize less than 17lbs?

clarks rec. a max pres for bleeding of 10 and your saying to test it at 12ish. which model do you have? or does the 12270 allow you to test at pressure below 17 and the manual is stating otherwise?

That is some good info. I am new to porsche 944 non turbo 1987. This question is to help me not question you. I thought the bleed valve was on the top of the engine. Why do I jack up the front end? I really appreciate your help. My car steadily get hotter as I run the engine until it is showing too hot. I bleed it but I did not do it that long or with the hose.

i echo what wayne says, im not questioning u granite, just looking for further insight..

i have that model stant on the way here as we speak. but reading the write up about it on the web, admittedly, after the fact, is when i recognized that it said the lowest 'test pressure' was 17.

perhaps i just need to wait to read the real book when it gets here...

Air travels to the top of water. There are also some places inside the engine where air can get trapped. By raising the front of the car, the air bubbles travel to the radiator and on the way pass by the bleeder location. I've never used a pressure tester to bleed mine but I do put my car on a sharp incline with the front up to bleed it using the hose method outlined earlier. I've never had any problems getting all the air out when I do that.

Man! you guys are relentless! ;) ;)

First point. You don't need to raise your car up/down/sideways or anything.........if your using a presssure tester to bleed with.

2nd point.

" if your referring to the stant 12270 it wont pressurize less than 17lbs?"

REALLY. I don't know where ya got THAT from, but, I'd have to guess your not using the tool properly, insuring that the pump cap is sealing up properly at the overflow tank. This stant comes with a rubber seal ring/spacer which you will need to use with your car. Are you using it? I can put my tester on, and pump it up to just about any pressure I so please. I would recommend starting at around the 10 psi range as is stated in other stated forums/procedures, till ya get a complete handle on whats going on with your car, and you know the condition of all components of your cooling system.

Basic quick procedure I use to bleed the system is:

1: fill coolant tank to midway point (cold).
2: pressurize with the tester pump to approx. 10 PSI. NOTE.......if your not holding pressure at 10psi without a massive/quick drop in pressure, than you need to make sure you've got the tester on properly, and or, you don't have some major leak somewhere. (IF ITS A LEAK somewhere, it should show itself pretty quick and easy at this point).
3: make SURE you have your heater valve open to allow flow in/out of the heater core.
4: open bleeder screw slowly to moderately (have lots of rags or whatever to cover/catch underneath that area) and watch the pressure gage and for air/foamy coolant as your letting all escape out of that bleeder. Close the bleeder valve when ya see gage get down close to zero, but not AT or after zero.
5: Pump the tester/system up again to 10psi, and repeat till you see/hear/feel no evil coming out that bleeder valve. It can take several times of repeat action.
6: Run the car. Bring it up to temp, and let the fans cycle on and off.
7: repeat the bleeding process while warm.

Experience will help ya here. If, you don't think ya got it good enough after driving a bit, simple solution is to repeat all above again. No fuss, no muss. You don't have to raise your car. You only do this as a recommendation, if you DON'T have a pressure tester to work with, because your now depending on gravity to help you bleed the air out, NOT pressure pushing the air bubbles/pockets out. (funny, brake pressure bleeders kinda work the same way. Another great tool to own. :))

These testers come in SO handy for bleeding, and FINDING coolant leaks, I think it should be a standard tool in anyones toolbox that is even remotely serious about working on their own cars.

If I missed something here, I hope someone else with the experience will jump in and help/correct me. :)

Good luck!

well that about cleared it up! thanks!
this is where i got the info. my unit wont be here for another week.
http://www.stant.com/brochure.cfm?brochure=578&location_id=183

i think i may have misread it.

Well, ya just made me go out to the garage and look to see what model of stant I have. YEP, it is the same one I have.

Note on the description where its says......"The Stant 12270 tester allows you to test today's cars higher pressure cooling systems and pressure caps up to 30 pounds"..........key being.........."up to".

The statement of......"The gauge includes new cap testing pressure ranges of 17-19 lbs., 20 lbs., and 28-30 lbs." is regarding only caps with the newer/higher type release pressures on some of the newer cars. An added bonus here.

This tool should be all ya should need for this car, and many, many others. :)

You'll find it a great tool! You can also do some diagnostic checks with it regarding situations like a possible head gasket leakage problem also, AND, you can easily check the cap for proper operation also. Enjoy, and the instructions included with it will make all much more clearer. :)

Now.........regarding the mess of bleeding coolant all over the top of your engine...........well.........the bleeder valve idea may make things nicer, and, I personally haven't done anything regarding finding a better way of avoiding making a coolant mess (other than the rags all around), so you might go after this one next, if you so desire. I find I don't have that much of an issue with this, so I haven't gone outta my way to re-invent the wheel here.........much. ;)

"The gauge includes new cap testing pressure ranges of 17-19 lbs., 20 lbs., and 28-30 lbs."

it does seem to say that 17 is the lowest...
and it doesn't test between 20 and 28..

but maybe i'm reading it wrong too..

Serves me right for trying to comprehend stuff after a 16 hour day at work, your 100% correct and i misread, it was regarding the CAP.

thanks again Granite.

Id like to give my cooling system a test, because if i fill it to MAX, the system seams to leak until there is about two inches over the MIN mark, then it magically stops leaking.

Sometimes i'll find literary, a drop of coolant on the floor near the front left side of the radiator after returning from a drive after filling to to max. then like i said, it'll leak down to the same spot very slowly over a month or two and just hold there.

yea i see where i misread too...

I'm the same way, EMB.... or rather, my coolant system behaves the same way.. leaks down to one point then stops...

this happened after my cooling system was flushed.

but i kept refilling it and eventually it stopped... so maybe it was just a bunch of air in the system that eventually worked itself out (over the span of about 6 months.. lol)

our cars are retarded Kyle, i just hope i dont open a can of worms, i really should leave well enough alone :)

but im glad to hear mines not alone, i'll have to test the cap when i get this thing maybe thats it?

on a side note, it is nice to know that both of our cars have freshly painted wiper arms. thanks for the motivational thread you posted a week ago by the way.

LOL
it's just my rear arm that's painted... the fronts are coming soon! my next 'little thing' day :P
along with stripping and repainting my passenger rocker..

Good tool the Stant, all the power to ya!

The grease fitting and clear hose method can be used with the Stant tool to avoid some of this mess. The total parts cost is like $3 or $4 and the coolant coming out of the bleeder hole can either be routed to the coolant tank or to another container.

IMO while the engine is running the coolant moving through the engine helps to move the air to the bleeder hole while the warm coolant expands to fill the air pockets.

I've had my 944 for a while now and I've tried the other methods of bleeding the cooling system on Clarkes Garage or Pargon's Tech session but the grease fitting and clear hose works pretty well for me.

Everyone should use the method that they feel is best for them.

--warning major thread drift--
Kyle,
do you have any thoughts on finishing those panels between the door windows and the 1/4 windows, those black strips? Mine are factory, and look it, the car was repained recently but they didnt do the wipers, washer nozzels and those black strips.

Im afraid if i sand them, and just use the same crappy rustoleum spray paint i'll be regretting it in a year. wiper arms are one thing the body is another.

PS. how far are you from Ottawa/Torronto? i end up in the big Canada cities a lot for work, one of my favorite places to go, Ottowa and Quebec city .

Mark, the sharpest thing I've heard said yet here.

"Everyone should use the method that they feel is best for them."

Thanks!

Kyle and EMB.

I've found that with all three of my early cars, that the "normal" level in the coolant tank varies between these cars. My '83 seems to like the level of just about an inch above the min. level when cold, and one car likes it a little higher than than, and the other, well.........jury is still out on this one, as I DO have some leakage problems with this one that hasn't been addressed yet.

In other words, just monitor what level in the coolant tank YOUR car prefers to run at, don't worry to much as long as it doesn't get to, or below the min. mark. Every car will vary on this, ya know.

IF, I fill ANY of my cars to the "max" level, yep.......it'll puke out what if needs to, to get to "its" desired level. Just note that level, don't fight it.

:)

major relief here, thanks Granite for the great info!