Today I changed a freeze plug and replaced my coolant. I now have no leaks and the car does not overheat. The problem is the system isn't building any pressure. The system built pressure just fine before I changed the plug (even though the plug was slowly leaking coolant). I filled the rad with coolant just below the cap. The cap and thermostat were replaced a few months ago, so I know they are fine. Could it be air in the system? Would that cause it not to build pressure? Any advice would be greatly appreciated. Thanks guys.
No pressure in radiator...need some help.
- Thread starter oldjunk
- Start date
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1968FormulaS340
Well-Known Member
How long did you let it run before noticing it didn't have any pressure?
I ran it with the cap off for about 15 min...hoping it would bleed out any air. Put the cap on and drove it about 5 miles. After the drive I checked and noticed it. Before I posted I put a pressure tester on it. When I started it had 15 lbs it now has 5lbs.
1968FormulaS340
Well-Known Member
Take it for a real drive and allow it to get up to full operating temperature.
15 minutes with the cap off followed by a 5 mile drive won't tell you jack about how your cooling system is functioning.
15 minutes with the cap off followed by a 5 mile drive won't tell you jack about how your cooling system is functioning.
Yeah, I guess I should have started this project a little earlier. It was getting late and didn't have enough time to really drive it. I'll give her hell tomorrow. After I replaced the thermostat (180 degree) a few months ago, I notice the gauge won't go above the 1/4 mark . Before I changed it, the old thermostat held at the halfway mark. Would you recommend going back to the old thermostat, or will the 180 degree be fine?
1968FormulaS340
Well-Known Member
If you are playing with the cooling system it would be a good idea to run an after-market gauge that shows the actual temp. You can hook one up temporarily.
I don't know what a temp of 1/4 or 1/2 is.
You really need to know what is going on. Hell, everything may be fine.
It sounds like you don't have pressure because it's running cooler and will take some time to get up to temp, 180 degree T-state is as low as I would go, they need to get up to temp!! Drive up a steep drive way and back out and run it hard and safe :coffee2:
Then tune everything in and run :coffee2:
I touch the engine to see if it is really getting hot.
You will know if that engine is getting up over 205..210
then you will have pressure
You will know if that engine is getting up over 205..210
then you will have pressure
I touch the engine to see if it is really getting hot.
You will know if that engine is getting up over 205..210
then you will have pressure
I got one of those digital thermometers...not sure i really trust that thing. I will play around with the car again tomorrow. Thanks for the advice!
Bulldozer
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i run a 195* thermostat, a 7 blade fan and shroud. my factory gauge barely gets to the normal operating temp line. i can drive it all day long and it will never get any higher than that. my heater blows very hot air and i never blow pressure or fluid into my overflow. i think you are overthinking it and it will be fine the way it is. go out and put some miles on it .make sure you have hot air coming out of your heater, pull over somewhere and make sure you arent leaking anything. and take some water just in case..
daredevil
Well-Known Member
maybe a leaking heater core?
Bulldozer
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slantsixdan
=..=
No pressure in my cooling system either, but that's 'cause I'm running waterless coolant with a very high boiling point even without pressure. Easier on all the seals, hoses, gaskets, radiator seams, heater core seams, etc. (Sorry, I know that's not helpful to you). The advice you're getting is sound, and also don't assume your pressure cap is good just because it's fairly new.
Bulldozer
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excellent.....
I guess I spoke to soon. I put the tester on the rad and now I have a leak elsewhere. I now have a very small leak from what looks like in between the drivers side head and intake manifold. I can see coolant slowly seeping down area where the timing chain cover meets the block. I guess the intake gasket is bad at the coolant port. Any way to be sure before I tear into it? If it's leaking on the outside, I guess it could also be leaking on the inside...:sad7:
Bulldozer
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are you positive it isnt coming from the water neck and trickling down? or from a heater hose?
I wish it was, I looked over the water neck and the bypass hose really well...not that. I guess it could also be a bad head gasket. The thing that really concerns me is the fact that the coolant looks like its coming from behind the timing chain cover. I just hope the block isn't cracked.:angry4:
BillGrissom
Well-Known Member
It may not be the intake gasket leaking. I say this because I had a small leak there (passenger's side) and it made a hissing sound as water came out. This was my first time running the car since installing another intake. I put a 67+ Edelbrock on my 65 and had to use flat-head socket screws to match the countersunk holes to get the angle right, hence couldn't tighten the screws enough. That leak stopped after tightening a bit more (or with time). I got a few other leaks, probably because I ran coolant flush thru before installing the radiator (connected upper and lower hoses together). I seemed to have had a leak from the rear, probably from the core plug, but seemed to have stopped. Last time I ran it, it appeared to have a small one from the head (exhaust side). They will probably seal themselves since it had no leaks originally. If not, I will try a little AlumaSeal.
Bulldozer
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well, before you get worried, like bill said, it may seal itself up. in the mean time, i would get a socket on it and try to get another 1/2 turn on the front cover bolts and double check the torque lbs on the intake.
Bulldozer
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it looks to me like the water port gasket between the block and cover is the suspect.
When was the last time the cover was disturbed? If you had the cover off did you use a non hardening thread sealant on the cover bolts? Some of then go into water. Did you use sealant around the water jacket ports when you put the intake on?
Just some things to consider.
I had a small leak in kinda the same area and after draining part of the coolant and pulling the cover bolts, putting some sealant on them and reinstalling the leak stopped. It appears that it was bleeding around the threads and pushing out.
Just some things to consider.
I had a small leak in kinda the same area and after draining part of the coolant and pulling the cover bolts, putting some sealant on them and reinstalling the leak stopped. It appears that it was bleeding around the threads and pushing out.
So there are ports between the timing chain cover and the block. I was unaware of this. Just thought there were oil ports there. Thats gotta be whats leaking. I'm wondering if I should just pull this motor and replace all the gaskets/freeze plugs.
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