coolant pressure with a cold engine ?

classicalgreen

Active Member
I am using waterless coolant in my 3500 auto. have been moving it up and down a short drive while not on road to keep things free and moving such as brakes! I ran engine for about 5 mins varying speeds from idle to about 2500 .engine has no thermostat fitted ta moment. about 3-4 days later I thought I might check oil and water. when releasing rad cap about a cup full of. coolant shot out everywhere.. so there is pressure rebuild up. cll pressure checks. show all within 10% of each other and oil is clear ..no mayonnaise etc . as was thinking suspect head gasket fail but surely pressure ought to reduce after such a time with stone cold engine? I normally top level too cover. calling fins in rad. leaving decent. room fo rain expansion. No header tall fitted and a 15lbs cap being used /no external coolant leaks found. Oil leaks another thing! anybody have ideas? don't fancy having to remove both heads but only fault I have noticed is when In heavy traffic on hot days or travelling at. near legal speed limit ( rare) temp gauge will climb past midway..rad has been off car and back flushed. and drained ( twice) engine and heater matrix also back flushed . marina debris ( rust?) found bottom of rad near inlet hose but about half a cup at most whole rad.. my thoughts are thats if got to be heads off at some stage and check for porosity and resave will full gasket set . wife isn't keen on car anyway as a money pit so trying to keep expenditure to minimum and time 'not running' out of her vision. any. pointers. would Venice of anybody had this ?
 
I don't know why you would still have pressure after 3 or 4 days, but I would not worry too much, if it is not puking out everywhere on a run let it be.
Running without a stat is not good, why do you do that ?
I use Evans and have run at zero pressure, but I did find that the recovery bottle I have filled with a lot of coolant due to expansion. I got a rad cap and cut the spring to make a cap with about 5 psi pressure, now the bottle level only changes by 2 1/2 " or so. BTW I fill my rad to the brim with the motor running fast and then slam on the cap. The coolant in the bottle gets sucked back in the rad as it cools as I have a double seal cap.

You can get coolant sniffer kits cheaply to save pulling heads unnecessarily.
Eg BLOCK HEAD GASKET TESTER KIT COMBUSTION LEAK PETROL DIESEL FX53 KIT 100ml 2d 616241345390 | eBay
 
might have to think about getting an expansion tank fitted ! I am using Evans too. car still suffers not overheating but gauge shows well past mid section when on any high speed or in heavy traffic ( luckily rare) I did try jacking car up once at front and adding fluid as engine ran ( above idle) so can see fluid going over fins. topped up to cap level and put cap on. same result. even though ensuring a such air out of system as possible. though fluid ejection was overfilling.. so allowed it to expunge any excess via over flow tube form rad to road. will keep using car at moment but an very puzzled why pressure in system days afterward with a stone cold engine and I mean cold!
 
I can't answer your residual pressure question. I would try fitting a double seal cap and a recovery bottle. I fill my radiator as stated above and then have about an inch of coolant in the recovery bottle with the pipe going below the coolant. This way the system manages itself well and every time since I have looked in the rad when stone cold it is brim full and the recovery bottle level is where I started.
I was surprised how much the Evans expanded, it is a lot at zero pressure, you however are still running at 15psi so it should be contained.
Evans does behave differently to a water/glycol mix, perhaps you just need to get used to its foibles.
If you have doubts about a head gasket issue, then test before getting your spanners out.
 
agree.not keen major strip down and rework if its not a gasket issue. at least its off road for 3 months ;) until hopefully the lock down abates .
 
I was surprised how much the Evans expanded, it is a lot at zero pressure, you however are still running at 15psi so it should be contained.
Evans does behave differently to a water/glycol mix, perhaps you just need to get used to its foibles.

we found similar on a P4 which only has a 4 psi rad cap. we needed to leave nearly as much air gap in the top of the rad as you would with normal coolant, otherwise it just pushed out the overflow
 
Yes that makes sense. I made my cap 5 psi by cutting the spring and then testing by pressurising the system through a pipe stub with an airline and gradually increased pressure from a couple of pounds upward until the cap lifted. I was able to keep trimming the spring until I arrived at 5 psi.
It was pure guesswork on poundage, but that seems to contain enough coolant to not fill the recovery bottle.
I wanted to drastically lower the poundage in the cooling system to give all the elderly components a nicer time, but zero psi was a step too far.
 
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