DrZ1

I have a coolant leak around the waterpump, I plan to take the car to Terry Simon, who has been a huge help on friday. I would like to see if I can source the leak before.

I was told I could rent a pressure tester at say auto zone , how complicated?

If i want to try to visulize while running, can I do this on jack stands w/ only front elevated or just one side like drivers side. I figure it is not the best thing to run the car w/ one side jacked up but thought I would ask.

thanks
Steve

The car seems to run warmer at idle, but put under control w/ ac on. no sure if the leak is from pump, hose or thermostat. Dont want the pump to sieze.

dand86951

Pressure tester is easy to use, just take off the rad cap, be careful if your engine is hot, put the pressure tester on in place of the rad cap, pump up the pressure to about 1.5 bar (approx 21.75 psi). Then look for the leak. It would be a good idea to have the car up on jack stands or preferrably a hoist to be able to look from the bottom.

Check with some shops about a special light that makes a coolant leak really show up. I don't know the exact name but one shop had one and I found a leak out of my turbo water pump that was otherwise very difficult to trace.

xsboost90

the coolant system usually peaks at 15psi- which is why the cap is rated 14-16 lbs usually- i would be careful putting 21 psi in there.

DrZ1

I was wondering how much pressure to run, since I am hoping I dont have a head gasket problem or wnt to create one. I changed the oil last weekend and there was no water in the oil. I seem to be losing the entire resivior of coolant in approx 150-200 miles, I do not smell in car but can smell some at the right front. given the amt lost I feel that I must be loosing at boost sice I cant see at idle but will try to pressure test.

thanks for the input
Steve

ehall

I've done this a number of times. Once you get to 10psi you don't need any further preasure. If you have a leak, it will be painfully obvious at 10psi. There is absolutely no reason to go higher unless it is your mission to find (ahem... create) holes in otherwise serviceable hoses. If they are a tad weak or worn around the hose clamps, 15 psi or more will turn those weaknesses into leaks.
As far as jacking the car, it may well not be neccesary. If someone else is working on it, you will save him time just by pointing to the hose, or close to the spot. I would first look for the leak without jacking the car. It doesn't matter if you jack one side or the other, if you find that you need to get under the car to pinpoint the leak.
Wear eye protection when you go nosing around for a preasurized coolant leak. Also keep the pressure tester long enough to bleed the system once the leak is repaired. You'll save yourself a giant headache.

bearone

but remember a 15psi cap on an older vehicle is over pressurizing the system and the postor didn't say what year.

87951

DrZ1

Sorry, The car is a 86 turbo

Steve

bearone

check the cap 1st as was suggested to 15 psi.

87951

DrZ1

"check the cap 1st as was suggested to 15 psi."

Are you saying make sure the pressure is set to 15 on the cap or make sure the cap is working properly

thanks
steve

dand86951

The factory radiator cap for the 951 is rated at 1.5 bar or 22psi. The 951 cap is different from the 944 cap. Obviously Porsche knew the engines were going to create some extra heat and thus higher pressures than a 944. If you only test to 10 psi that is fine as long as it catches the leak. If you have a leak occurring only when the coolant system is at max pressure then you may not catch it. If the hoses clamps etc won't work at the rated cap pressure then they should be replaced also. Good luck

dand86951

To check to see if you are losing it under boost then pull the black (if Original) vent hose that goes from the coolant tank by the rad cap down under the car up and reroute it to a water baottle with a hole drilled in the cap just big enough to fit the hose. You can set this down under the headlight mechanism and for a temporary check duct tape it to the car. Go drive the car and periodically check the level of coolant in the water bottle( of course empty the water bottle prior to using Drive the car for some distance without getting into boost, I know that's hard but you just have to watch the right foot.

If you don't have any overflow after that then go out and drive the car hard. Then check to see what you have in the bottle. If you have coolant only after boost then you probably have a headgasket problem. The first step in all of this would be to verify the coolant system is bled properly to try to get as much air out of the system as possible as with airpockets you can get localized heating and get steam created that will overpressure the system and it will then vent out past the rad cap.

bearone

show me something where the cap is rated @ 22psi, mine shows 16 on the cap and pelican shows two caps, early/late.

drz1
check the cap to 15 then the system if the cap holds pressure ok.

87951

dand86951

Bearone, this info is straight out of the Porsche Workshop manual on the specs for the coolant system for the 951. Pelican has this one wrong and I think you have the wrong cap if it is only 16 psi. If that one is working for you then that's great but it is not the one specified by the factory.

If you want a copy then PM me and I will send a pdf file for that page to you.

You are absoluetely correct is saying check the cap for its rated pressure. Even brand new caps may not meet the specs. as I have found.