cooling system pressure testing

#1

morning guys,

Can anybody recommend a cooling system pressure testing kit that actually fits the E30 set up please.

I’m still having issue bleeding the system, I’ve flushed and re-filled the system, new thermostat and will change the rad cap next.

The hoses appear to go rock solid when the car is running, it doesn’t overheat as such, the after market gauge is showing 200oF and a lazer temp reader confirms that temp at the sensor in the housing.

The water pump and timing belt have about 1000 race miles on them, head gasket was changed at the track last race due to another head failing?

I’d like to diagnose a HG problem rather than pull the head again!

Thanks

#2

This kit has adapters that fit both early and late model reserviors.
http://www.harborfreight.com/radiator-pressure-tester-kit-65053.html

If the problem is only a bleeding problem, I don’t know that I’d suspect the HG. The first thing I’d do if the problem was kicking my ass, is pull the tstat and drill a very small hole in the top of it. This will allow trapped air to get to the bleed screw even tho the tstat is closed. This lets you bleed the system immed. instead of waiting for the car to warm up so the tstat will open.

#3

Thanks…we took a break from the car last night but will drill a hole in the new Tstat when it arrives…well worth a try…

We sometimes seem to have a problem bleeding the system and other times its fine…I also want to try the blanking plate delete (matrix already removed) as I think the T shaped fill hose is causing an issue (one end on the thermostat housing and the other on the back end of the head? Im imagining a huge air bubble in the middle that cant find its way out…

Thanks again…its off to China Freight later!

#4

Morning guys,
Just wanted to follow up on this question I asked help on…

Got a new thermostat and drilled the hole in the top edge, also bought an HF pressure test kit…

Did an initial pressure up to 15psi and found we had a drip from the thermostat housing. Depressured it and resealed the joint.

Had problems holding pressure, I ended up block off the overflow tube (not sure if thats correct, I think im right in saying that when the rad cap is on, this path is sealed between the 2 O rings unless a high pressure exisits?

Anyway, still thought we had lots of air in the system, even though only water was coming out of the vent prot on the thermostat housing.

Here’s the key school boy error admission. We did an engine swop a while back and put in a 1989 engine and the expansion tank was on the opposite side. We mounted it slightly lower that the OEM location due to a damage bracket and it was just too low to allow air to naturaly travel out of the top of the radiator and up to the expansion tank…so when I moved it up about 2 inches…I got another half pint of water in the system! DOH!!!

When running all was good…

Am I supposed to be able to run the car with the pressure tester on the expansion tank and see what pressure is in there? The gauge didn’t read anything?

Anyway, thanks for the help on this one!

Mark

#5

I would remount the overflow tank so the max fill line on the tank is atleast the same height as the highest point of the radiator. As you found out air will work its way to the highest point in the system. Last thing you want is to be on track and you loose water and run in to your same problem again.

On the older cars, you can mount the overflow tank a 1/2in higher and still have plenty of clearence with the hood.

#6

Another hint I’ve used is to raise the front of the car when bleeding the air. That seemed to help my street car quite a bit.

#7

Thanks guys, all taken onboard. The expansion tank is now as high as it can be under the hood and all seems well again!

I did a compression test and all cylinders seem good too, so hopefully we are ready to race on October 1st/2nd in Houston!