When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
That may be so....but I have......seen manifolds and headers glow red......which is like 1100 degrees......especially under a load.......and this heat transfers into the cooling system......
Check the timing and rule it out.......most GM HEI's are 15 initial/36 total......
Jebby
ok I will make sure timing is good .
BTW my manifolds are not red or running hot
This is a complete mess. You need a new Radiator, you need to check the timing and you need to put back the engine driven clutch fan and all your problems will be solved. Also, your vehicle wiring is not set-up for a 150Amp Alt, you run the risk of fire with the old, undersized wiring.
Can you ask your mechanic what he set it to? Or, better yet, get a digital timing gun and DIY.
IR temp gun, too.
I will ask n i don't have a timing gun
or ir gun but my Temps are reading correctly or it wouldn't boil over at 250
n fans wouldn't kick on at 180 like they are .
I appreciate all the help
I am NOT real good with electrical at all!
but I worked on cars long enough to know what it's NOT!
and temp reading with ir gun and timing isnt the issues i can guarantee that !
but I will do both to confirm that with you .
I think some people aren't reading the whole thread
this just started happening
With same set up that's been in there the past year .
it runs n drives perfect
Bad timing isn't going to make it Make it do this overnight
one day it didn't overheat n ran great next day it runs great but overheats .
the only thing that is new n changed on the car the day before I bought it was the carb and that's when he ran that hot wire to choke to that circuit breaker
I'm thinking like u said before it's resetting that breaker.
it didn't do it before he installed that wire
so I'm going to run new wire to hot wire to wiper motor and run a new bus bar for the 2 relays for fans n eliminate the breaker all together.
it's already got inline fuses n relays !
Last edited by Rick Trotta; Jul 17, 2023 at 11:34 AM.
This is a complete mess. You need a new Radiator, you need to check the timing and you need to put back the engine driven clutch fan and all your problems will be solved. Also, your vehicle wiring is not set-up for a 150Amp Alt, you run the risk of fire with the old, undersized wiring.
I'm not going back to stock fan n shroud
too expensive and these fans n radiator ran great for the past year when they were put in
I can't blame the radiator or fans.
that's plenty enough to cool motor down when they are working properly
something is causing the fans to shut off and not come back on.
A lot of smart people in here.
but TIMIMG is NOT my issue !!!!!!
I am running new wires today for new alternator
Timing is good
I worked on enough cars to know what bad timing is !
not to mention I had it checked
i do trust my mechanic and vehicle start right up n runs perfect .
going back to old fan n shroud isn't an option !
But appreciate the feedback .
rememeber it ran perfect with that setup for the past year !
the only thing changed before I bought it was he put a carb on it n ran the hot wire to choke from that breaker the fans are on now !
I also verified the radiator is flowing nicely
hoses are good
New water pump and thermostat even ran it without thermostat
It's definitely wiring or open or short
like i said I'm not much on electrical
but I do know my fans and radiator and shroud are great !
so is my plugs and timing !
Everything is damn new at this point .
I'm going to replace all wires and run it the way this thread said it to run it
from starter not alternator
Which I'm not sure why that would make a difference but I will try it !
thanks again
If your radiator is not cooling properly, you will not see a temp gradient across the radiator. If your rad cap, or some other component, is not holding pressure, you will see boiling over as low as 212 deg F. I don't trust my temp gauge, I made my own Arduino-based temp sensor, and still carry an IR gun. You can quickly diagnose either issue, and we can stop speculating.
An IR gun is $10- at Harbor Freight, or $15- at Amazon.
Likewise, if you didn't time the car yourself, you don't know the timing. If your mechanic set the static timing (per the shop manual) it is almost certainly retarded. If he didnt check the vac advance, it could be retarded even more.
The item circled in the pic is a thermal circuit breaker. When the car is cold check to see if you have continuity between the posts......you should get it. Now when the fans aren't working as they should re-check for continuity between the posts....if no continuity the breaker is doing it's job....possibly failing earlier than it should.
I'm not sure what size wires you are using, but replace with a compatible breaker for the size of wires.
The item circled in the pic is a thermal circuit breaker. When the car is cold check to see if you have continuity between the posts......you should get it. Now when the fans aren't working as they should re-check for continuity between the posts....if no continuity the breaker is doing it's job....possibly failing earlier than it should.
I'm not sure what size wires you are using, but replace with a compatible breaker for the size of wires.
I'm thinking the same thing and replacing it with a bus bar today and all new wiresthank you !Will keep everyone updated
I'll tell you all this.
if it's the timing I'll buy everyone in this thread lunch for the day!!
that's how sure i am its not the timing !!
You have to look at it from our point of view: you rely on a mechanic to set your timing, so we have to assume you aren’t knowledgeable in timing an engine. Yet you are stating unequivocally that timing isn’t the problem. How do you know that if you aren’t knowledgeable in timing? This is why people keep suggesting to check your timing.
I am an old hot rodder for almost 40 years, returning to the hobby just recently. I thought I knew a lot until I joined this forum.
A side note on timing: many on here recommend NOT using OEM timing/tuning specs because they were, at the time, geared towards reducing emissions. This almost always results in a hotter running engine. Most mechanics will follow factory setting because that’s what they do.
Also, try not to hang your hat on the fact that it happened “overnight”. While a good tool for helping narrow down the problem, I’ve seen many a time where the problem was long standing elsewhere and something small changed and it was the “ straw that broke the camels back” and made it seem like it happened overnight.
We’re all just trying to help a fellow Vette head here, so take a breath, go back to the beginning and start over. We’ll get you fixed up.
You have to look at it from our point of view: you rely on a mechanic to set your timing, so we have to assume you aren’t knowledgeable in timing an engine. Yet you are stating unequivocally that timing isn’t the problem. How do you know that if you aren’t knowledgeable in timing? This is why people keep suggesting to check your timing.
I am an old hot rodder for almost 40 years, returning to the hobby just recently. I thought I knew a lot until I joined this forum.
A side note on timing: many on here recommend NOT using OEM timing/tuning specs because they were, at the time, geared towards reducing emissions. This almost always results in a hotter running engine. Most mechanics will follow factory setting because that’s what they do.
Also, try not to hang your hat on the fact that it happened “overnight”. While a good tool for helping narrow down the problem, I’ve seen many a time where the problem was long standing elsewhere and something small changed and it was the “ straw that broke the camels back” and made it seem like it happened overnight.
We’re all just trying to help a fellow Vette head here, so take a breath, go back to the beginning and start over. We’ll get you fixed up.
i appreciate all of you for all your help!!
I'm just simply saying
I trust my mechanic and I do no how to set timing
I just don't have a gun with me at the moment. I'm in the process of moving and all packed up!
I'm just not real good with electrical!!
I am taking everyones advice to heart !
I'm just letting you all know we can rule that out along with everything else I mentioned I already tried or replaced .!
so we can move on from those things and try something else!
I posted a pic of alternator and a green wire laying next to it that wasn't hooked up
that I'm concerned with and also the high idle after replacing alternator!??
I am replacing that circuit breaker today!
I think that choke beinf plugged into that breaker for the fans might be my problem
it makes the most since!
i just keep mentioning timing cause everyone keeps suggesting it .i already rulwd that out !
I don't think I know everything at all which is why I'mwhy here asking for help!
I just don't want to keep going after something I know it's not
my mechanic assure me its timed right n I trust him
Not to mention. All the symptoms dont lead up to bad timing .
again i do appreciate all the advice
agai.lets just move on from timing n take my word for it's good.
You have lots of eyes on this thread who want to help. Eliminate this possible issue, and move on.
On the road, your car should not need those fans to run at all to keep the engine cool.(unless, as pointed out, you have a high-stall TC). So while you should absolutely replace that circuit breaker, and also beef up the alternator charge circuit to match the alternator, I contend that the fans not running this is just the "straw"", and not the problem.
If you are in NoVa, I'll happily loan you a timing light and help you confirm the timing. I'll buy you lunch if it is set correctly.
You have lots of eyes on this thread who want to help. Eliminate this possible issue, and move on.
On the road, your car should not need those fans to run at all to keep the engine cool.(unless, as pointed out, you have a high-stall TC). So while you should absolutely replace that circuit breaker, and also beef up the alternator charge circuit to match the alternator, I contend that the fans not running this is just the "straw"", and not the problem.
If you are in NoVa, I'll happily loan you a timing light and help you confirm the timing. I'll buy you lunch if it is set correctly.
you are right as far as not needing fans on highway
But when in stop n go traffic and red-lights you do need fans especially in 90° days !
that's when it starts running hot now!
all I know is when i got the fans to come back on
I drove it the rest of the way home n it never went iver 200°
n it was a good ride home .
I'm sure ur right
that wasn't the only issue.
I think flushing out my Radiator certainly helped!
a new waterpump n thermostat N alternator certainly didn't hurt n was do for upgrade anyways.
i will ssk him today what he set timing at n let you know so we can rule that out for sure.
I'm not going back to stock fan n shroud
too expensive and these fans n radiator ran great for the past year when they were put in
I can't blame the radiator or fans.
that's plenty enough to cool motor down when they are working properly
something is causing the fans to shut off and not come back on.
A lot of smart people in here.
but TIMIMG is NOT my issue !!!!!!
I am running new wires today for new alternator
Timing is good
I worked on enough cars to know what bad timing is !
not to mention I had it checked
i do trust my mechanic and vehicle start right up n runs perfect .
going back to old fan n shroud isn't an option !
But appreciate the feedback .
rememeber it ran perfect with that setup for the past year !
the only thing changed before I bought it was he put a carb on it n ran the hot wire to choke from that breaker the fans are on now !
I also verified the radiator is flowing nicely
hoses are good
New water pump and thermostat even ran it without thermostat
It's definitely wiring or open or short
like i said I'm not much on electrical
but I do know my fans and radiator and shroud are great !
so is my plugs and timing !
Everything is damn new at this point .
I'm going to replace all wires and run it the way this thread said it to run it
from starter not alternator
Which I'm not sure why that would make a difference but I will try it !
thanks again
Run from starter instead of alternator to reduce the length of wiring. Reduced length equals reduced resistance of the wiring, reduced resistance allows the current to flow easier reducing the load of the Circuit. Also the wiring lugs are larger at the starter allowing for larger wiring and connectors. Actually going to the battery is better than the starter. And the thermal breaker shown in your pics will not handle the load of your fans, that looks like a breaker for the headlight circuit. Running without any fan shroud or a reduced area shroud will reduce the effective area the fans can pull air from. There should be a shroud that completely covers the tubes and fins of the Rad. I did all the stuff you are doing now and it did work but marginally but ultimately went back to the mechanical clutch fan and full size shroud and never looked back. Although ditching the Mechanical did give a HP gain but at what price. The electrical system did suffer though and felt is wasn't worth the extra HP gain. Been working on these $hitboxes for 45 years. Just saying.
according to him it does
I do trust him
He juat isnt cheap and doesn't have time to bring mine in shop now
plus I don't mind working on. My own car as long as I have all the tools and not just throwing parts at it !
Run from starter instead of alternator to reduce the length of wiring. Reduced length equals reduced resistance of the wiring, reduced resistance allows the current to flow easier reducing the load of the Circuit. Also the wiring lugs are larger at the starter allowing for larger wiring and connectors. Actually going to the battery is better than the starter. And the thermal breaker shown in your pics will not handle the load of your fans, that looks like a breaker for the headlight circuit. Running without any fan shroud or a reduced area shroud will reduce the effective area the fans can pull air from. There should be a shroud that completely covers the tubes and fins of the Rad. I did all the stuff you are doing now and it did work but marginally but ultimately went back to the mechanical clutch fan and full size shroud and never looked back. Although ditching the Mechanical did give a HP gain but at what price. The electrical system did suffer though and felt is wasn't worth the extra HP gain. Been working on these $hitboxes for 45 years. Just saying.
ok thanks i will run it that way as you say!
as far as shroud covering radiator thats how they come factory and worked for the past year.i don't think that's an issue to be honest!
I'm not really worried about gaining or losing hp to be honest .
just what the car came with
n expensive to go back to original especially if it's something simple as a breaker to fix it .
but if it isn't i might have to go back to original anyways.
I'm just trying to get it going so I can at least drive it this summer and i Wil do more upgrades n fixes while it's parked for the winter
I just got the vette about a month ago .
Bur agree on breaker not for fans
hoping that's all it Is
I'll find out tonight
Thanks I'll keep everyone updated!
anything as far as that green wire next to my alternator?
and why it might idle Over 2000 rpm at idle after alternator replaced?
anything as far as that green wire next to my alternator?
and why it might idle Over 2000 rpm at idle after alternator replaced?
The stock temp wire is called out as dark green. It could be that? It may appear from the harness near the alternator bundle. Wiring diagrams at the link:
Dunno about your idle. Does it drop down eventually? We still haven't seen photos of your carb (that I could find), so we don't know what is going on with your choke, etc.
BTW, here are a few threads with helpful alternator and fan wiring diagrams by @Richard454
If you just got it a month ago, are you certain that this hasn’t been an ongoing problem that the PO didn’t disclose or didn’t realize because of his/her driving habits?
