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What exactly are the symptoms when it overheats. Just high water temp indicated? Or is it boiling over into the overflow reservoir?
what heads ore on it now? Stock?
stock heads
And yes it boils over into the Reservoir and sprays all over the motor !!
if it was a head gasket or cracked head ..wouldn't it of failed the block seal test that I did ??
also what heads do you recommend ?? And should I replace the cam and intake and headers when replacing the heads ??? If that is the case!!
Saw a similar issue years ago on my Dad's Buick. Went through the usual stuff, t-stat 1st, then pulled the radiator and had it tested, tested OK.
thought the same thing as suggested, we changed the right head gasket. Saw no obvious problem with the gasket. Same issue, still ran hot.
Pulled the radiator again and took it to a different shop. Radiator was blocked solid. Radiator was rodded and cleaned. Reinstalled the radiator, problem solved.
Check your radiator.
stock heads
And yes it boils over into the Reservoir and sprays all over the motor !!
if it was a head gasket or cracked head ..wouldn't it of failed the block seal test that I did ??
also what heads do you recommend ?? And should I replace the cam and intake and headers when replacing the heads ??? If that is the case!!
Not neccesarily. The crack/head gasket leak opens up as it gets hot. Then combustion gasses get pumped into the cooling system. This causes the pressure to exceed the 14 psi rating on the radiator cap and blow the coolant into your overflow bottle and eventually overflow it.
Get one of these. It will tell you if combustion byproducts are in your coolant.
Not neccesarily. The crack/head gasket leak opens up as it gets hot. Then combustion gasses get pumped into the cooling system. This causes the pressure to exceed the 14 psi rating on the radiator cap and blow the coolant into your overflow bottle and eventually overflow it.
Get one of these. It will tell you if combustion byproducts are in your coolant.
Overheating at speed can be only one of two things.
And changing your heads isn't one of them.
Ignition timing or an inadequate radiator.
Is your vacuum advance can working correctly? Did this shop really check your timing? Or just set the idle timing?
Are your radiator and hoses really flowing correctly?
And checked for a spring in your lower radiator hose (go squeeze the hose, the test will take 10 seconds)
And confirmed the timing that your shop used?
If you don't have combustion gas in your coolant (excellent check BTW!), it's timing or coolant flow. You are probably one part away from solving this.
That would rule out exhaust gases in the cooling system causing the rise in pressure.
1) The boiling point of water is 212 °F at 1 atmosphere of pressure (sea level). 2) For every pound of pressure increase the boiling point goes up 3°F. 3) Typical radiator cap pressure is 12 to 16 psi. 4) This raises the boiling point of the engine coolant to about 250°F to 260°F.
5) Mixing ethylene glycol antifreeze with water in a 50-50 ratio increases the boiling point 11°F.
that's exactly what I used !
It stayed blue !!
Did not change color !!
Saying head is good!!??
If it passed that test then yes I would say the head and gasket are good.
The symptoms seem to indicate otherwise combined with the sudden onset. Maybe test it again to be sure?
If everything worked fine before the oil change and then there is a sudden change you have to think what could have changed so suddenly? Something failed. Think along those lines and investigate everything that can possibly suddenly fail in the cooling system or other system that affects the cooling system, which is a lot of items.
You automatic transmission cooling lines also run through the radiator. Does this car have a high stall converter? Is the trans slipping creating extra heat?
Start with low hanging fruit. Is the thermostat working properly? You could remove it and put it into a pot of water with a thermometer in it and see where it opens or if it opens. Even new thermostats fail. I never install one unless I test it first.
It could be that simple. Probably not. You did replace it and the chances of a new one being bad are not high, but higher than it used to be.
If all the simple items don't fix it then I would have to think that the radiator has issues. Some rust from the block broke loose and partially plugged the radiator?
It's the sudden onset that keeps bugging me. If this is in fact the case.
Last edited by REELAV8R; Jul 11, 2023 at 07:35 AM.
Since it used to be OK and then just started overheating try this........As a quick test remove the thermostat, bolt everything back together and take it for a spin....see if it still acts up
Any updates? Having a resolution in a thread can help dozens of future Forum readers who never post.
didn't want to update until I'm 100% sure it's fixed!
but for some reason it's not overheating now .
It's still running around 230 - 240° when on highway but hasn't overheated yet.
I'm thinking from it running hot and filling it back up several times might have flushed out the radiator n block ..I really don't know .
as we speak my car is running outside with cleaner in it .I'm giving it a good flush thinking maybe that's all it was .after I drain n refill it twice tonight .
I'm going to top it off and drive it tomorrow n see what happens.
It's definitely getting too much pressure build up!
Both my Radiator hoses upper n lower are hard to the touch when hot. I also noticed there was a 20lb cap on it .I put a 16lb on it .
it's definitely NOT the fans or shroud or timing or anything like that.That I'm sure of !
either a dirty n clogged Radiator which is fairly new?!
or getting air in it?!
I am changing plugs tomorrow n doing one more flush then will hopefully know after that if it's fixed or not!
but timing ,vacuum,shroud, fans wouldn't make it boil over only at high rpms that I'm sure of !
it might make it run hotter than normal but not boil over!
I will definitely keep everyone updated as soon as I am positive it's fixed !
thank you all !
didn't want to update until I'm 100% sure it's fixed!
but for some reason it's not overheating now .
It's still running around 230 - 240° when on highway but hasn't overheated yet.
I'm thinking from it running hot and filling it back up several times might have flushed out the radiator n block ..I really don't know .
as we speak my car is running outside with cleaner in it .I'm giving it a good flush thinking maybe that's all it was .after I drain n refill it twice tonight .
I'm going to top it off and drive it tomorrow n see what happens.
It's definitely getting too much pressure build up!
Both my Radiator hoses upper n lower are hard to the touch when hot. I also noticed there was a 20lb cap on it .I put a 16lb on it .
it's definitely NOT the fans or shroud or timing or anything like that.That I'm sure of !
either a dirty n clogged Radiator which is fairly new?!
or getting air in it?!
I am changing plugs tomorrow n doing one more flush then will hopefully know after that if it's fixed or not!
but timing ,vacuum,shroud, fans wouldn't make it boil over only at high rpms that I'm sure of !
it might make it run hotter than normal but not boil over!
I will definitely keep everyone updated as soon as I am positive it's fixed !
thank you all !
btw I did replace water pump ,thermostat both with upgraded high flow ones.
ordered new hoses with spring .
took off the belt driven fan.
addEd some foam around top of radiator.
but all seals are there already .
looks like the previous owner must of had these issues before because everything that is talked about in the thread and involves the coolant system has already been replaced. Of course when I asked him he said he never had problems with it overheating..I don't know
but as soon as I do
You all will !!
Last edited by Rick Trotta; Jul 13, 2023 at 06:39 PM.
Ok guys just giving an update.
flushing it did not fix it and was never the problem.
But I did find the problem.!
Not sure how to go about fixing it though if anyone has any suggestions ??
but my fans are shutting off intermittently when hot only ??
It ran in my driveway for over 2 hours today .
I took it out for a drive and it drove fine for over an hour on highway and all.
But then the temperature started to rise fairly quickly so I pulled over n popped the hood to see the fans weren't running!!I removed the relays to fans n put back in that did nothing. But then I tapped on the relays n the fans came on.i drove it home fine didn't overheat after that.
all the wiring looks good and relays n everything are new as well as radiator n fans !
also noticed the relays were very hot to the touch ??
do I need new relays or is it wiring or location of relays or what!??
I have no idea if anyone does i would appreciate any feedback .
thank you all !
Here is a pic of my relays and wiring for fans !
I thought fans didn't need to be on all the time when driving ?!
but as soon as I got them on it ran perfect...!
any help would be great!!
so the relays are bad?
getting hot?
I thought they handle up to 30amps?
so, fans pulling to much or alternator not putting out enough?
they are 60 amp relays per fan
I'm thinking the samething
maybe alternator isnt enough .not sure if its stock or not
but I just got a 150 amp alternator today from summit going to install it tomorrow n hope that fixes it
Either Way its due for an alternator upgrade .
i just checked online n looks like everything is wired the way it should be .
but alternator wires are shady so goign to replace them with alternator. N go from there .
Here is a pic of my relays and wiring for fans !
I thought fans didn't need to be on all the time when driving ?!
but as soon as I got them on it ran perfect...!
any help would be great!!
The reason your car doesn’t stay cool at speed without the fans running is because your restrictive shroud and non moving fans are blocking the airflow, versus a factory fan shroud setup that allows air to flow thru the radiator whether the fan is turning or not.
they are 60 amp relays per fan
I'm thinking the samething
maybe alternator isnt enough .not sure if its stock or not
but I just got a 150 amp alternator today from summit going to install it tomorrow n hope that fixes it
Either Way its due for an alternator upgrade .
i just checked online n looks like everything is wired the way it should be .
but alternator wires are shady so goign to replace them with alternator. N go from there .
do you have 60 amp relays?
that is crazy amount of amps.
is it 60 amps per fan?
