cooling system issue? m1009

[JamieM1009]

Hi all.
I recently replaced the rad, cap, t-stat, heater core, water pump and all hoses as the old rad had a hole in it and I thought I would replace everything after a few issues which seemed better after the pump was changed. my problem now is that when I've bled the air out with the cap off and then replaced the cap and turned the engine off. After cooling, the system draws some water back out the expansion tank and leaves the rad level a couple of cm below the top but if I drive it and get everything hot, once cooled it doesn't draw anything back out of the tank and leaves the water in the tank. Once cold I can put the water back in the rad manually and get it back to the same level but surely it shouldn't be doing this. Any ideas? Its not overheating when I drive it, I took it out for 30 minutes yesterday and all was fine except for this issue. Is it getting air back in the system from somewhere?

 

[JamieM1009]

Will not having the hockey puc type stat cause this? I think I have the other type.

 

[JamieM1009]

Just given it another run for about 45minutes on the motorway/highway. Its put out about 1.5 quarts of water in the tank and I can see some bubbles coming to the surface in the tank. There was no overheating and the water in the tank is only warm, not really hot or anything. Any ideas? Any help would be appreciated.
thanks

 

[phil2968]

I don't see a problem. If you fill a radiator full to the top it will push some out but then it should pull back in what it needs. Run it.

 

[JamieM1009]

I doesn't pull any back in and once cooled completely the rad level is down near the inlet from the heater core.

 

[MarcusOReallyus]

/scratching head/

Almost sounds like you have a vacuum leak that only shows up when hot.

 

[JamieM1009]

Yeah that's what I thought. It seems like its suckin in air when I drive along. Any ideas where from?
Are there any obvious places? I'm gonna recheck the fittings on the new rad. It came with a bag of brass fittings for the heater core outlet to plug in to the rad and for the low coolant sensor. I'll put some sealant tape round the threads and try that. Any where else?
I did think maybe it wad head gasket but wouldnt the exhaust gases escaping in to the coolant make it hot? The water in the tank was only just warm and the system ran at about 185 while driving

 

[DriverSideImpact1008]

You should have the cooling system pressure tested (or do it yourself if you have the equipment). By pressurizing the system you can find vacuum leaks, that wouldn't drip under normal operation.

 

[JamieM1009]

Unfortunately I don't have access to pressure testing at the moment. I had another look today and had it running for about an hour or so on the drive. It didn't overheat at all but I noticed that unless I pressed the throttle down there was nothing coming out of the heater outlet house and in to the rad. If I press the throttle then it pumps out but on tick over there's nothing. It also looks like all the bubbles are coming out of this pipe. The inlet pipe to the heater core gets hot quite quickly but the outlet isn't very warm. Seems like the hot water is pumped through the heater core inlet pipe but a vacuum won't let it pump out. Any ideas?

 

[salt6]

Go to one of the auto parts stores and borrow a tester.

 

[JamieM1009]

They don't really do that kind of thing over here. Stores don't really let u borrow anything

 

[timarr]

What about the rubber hose that crosses rad to the overflow tank, Maybe it has a crack in it and the rad only sucks air back?

 

[JamieM1009]

Well I had the block tester come and did a test. The fluid didn't change much but I would say it was almost green so there must be some gases present. If I leave it running with the cap off it doesn't overheat or push fluid out. I cut the rubber seal off the bottom of the cap so I can still put the cap on but it lets the gases out and they bubble in the expansion tank. Took it for a 25 minute drive and it ran fine, no overheating and any water that was pushed out in to the tank was drawn back in when it cooled. I'll get the head gaskets done as soon as I can and will have the heads pressure tested to check theirs no cracks. As long as I make sure it has coolant in and doesn't overheat how long should I be able to run it like this? I was thinkin of doing a thousand miles or anything but do have a few journeys to make before I can get it done.

 

[Buzz]

I was reading and if your guys block tester is the same as mine then the fluid is blue and will turn yellow if it detects combustion chamber gases in the coolant. With it changing to green, you very well may be in the beginning stages of a headgasket issue so I think you are on the right track. Did you say your heater core is hot going in but not coming out? If so did you try flushing it out with a garden hose, I see alot of heater core in all differant kinds of cars that will get sludged up and when you flush it you sometimes will have a big blob of junk come out of the heater core.
Hope you get it sorted out. Good Luck.
Buzz

 

[JamieM1009]

Hey buzz
I think your right about the early stages. When I bought the truck last year I quickly found out there was a hole in the top of the rad but it always drove ok, etc. Now that I've changed the rad and everything I guess the gas can't escape and the problem has become obvious. The head gasket has probably been leaking for a while and before I bought it. I only did 1200 miles in it last year so I'm not a high mileage driver, its more of a hobby vehicle that I take to shows for the public to see. If I can get through the 3 or 4 shows I have between now and September. I will have plenty of time to get it fixed. All the hoses are hot now that I'm venting the gas, if I don't vent it obviously the gas pressurises, coolant comes out, etc. The rad, pump, cap, stat, hoses and core are brand new.