El Camino Central Forum banner
1 - 16 of 16 Posts

·
Premium Member
Joined
·
1,298 Posts
There's a lot to this story, looks like a Dakota Digital dash, (I love mine btw) and I see you are running a 325hp 350 according to your profile? If I remember right a small block Chevy likes around 180-190 max temps while running. When the motor shuts off the coolant stops circulating so the hot iron keeps giving up its heat raising the coolant temp. I'm thinking your cooling system might be right on the borderline for enough cooling effect for your motor. I would start with the usual suspects. Fan clutch have enough tension? Next might be radiator? Does it have any restrictions? Capacity? Thermostat might be a bit high, maybe it's a 190 and a 180 could make a difference? A cooler thermostat may not work if the radiator is at minimal efficiency? I don't know your setup so these are really open ended questions so take this as an inquiry. The more info the better the diagnosis. My LS engine is happy in the 200-220 temp range here in Texas too. No boil overs but I am running a radiator rated for 800hp so my measly 400 doesn't even make it sweat. Hit us up with some details and hopefully someone will hit the nail on the head for you!
 

·
Registered
Joined
·
1,164 Posts
When you shut the motor off and then lose antifreeze you need to check your cap. Happened to me on my boat. 1 motor fine the other overflowed. Switched caps first because I did not believe this old guy. That was in 1990. Guess who is the old guy now. Needs a 15lb cap. Make sure antifreeze is 50-50 or less.
Tom
 

·
Premium Member
Joined
·
76 Posts
Discussion Starter · #6 ·
When you shut the motor off and then lose antifreeze you need to check your cap. Happened to me on my boat. 1 motor fine the other overflowed. Switched caps first because I did not believe this old guy. That was in 1990. Guess who is the old guy now. Needs a 15lb cap. Make sure antifreeze is 50-50 or less.
Tom
Thanks Tom, it was an NOS GM/AC Delco (RC27) I picked up, shows a 15lb pressure rating. Doesn't mean it isn't faulty though. Think a new cap, thermostat, and fresh coolant are a good idea.
 

·
Premium Member
Joined
·
76 Posts
Discussion Starter · #7 ·
There's a lot to this story, looks like a Dakota Digital dash, (I love mine btw) and I see you are running a 325hp 350 according to your profile? If I remember right a small block Chevy likes around 180-190 max temps while running. When the motor shuts off the coolant stops circulating so the hot iron keeps giving up its heat raising the coolant temp. I'm thinking your cooling system might be right on the borderline for enough cooling effect for your motor. I would start with the usual suspects. Fan clutch have enough tension? Next might be radiator? Does it have any restrictions? Capacity? Thermostat might be a bit high, maybe it's a 190 and a 180 could make a difference? A cooler thermostat may not work if the radiator is at minimal efficiency? I don't know your setup so these are really open ended questions so take this as an inquiry. The more info the better the diagnosis. My LS engine is happy in the 200-220 temp range here in Texas too. No boil overs but I am running a radiator rated for 800hp so my measly 400 doesn't even make it sweat. Hit us up with some details and hopefully someone will hit the nail on the head for you!
Radiator may be stock for the the vehicle, came with it when I purchased... VIN says it was originally the 307ci V8, so might need to go bigger. But, this overheating on shutdown is new, have not experienced it before the last 2 times I took it out for short local drives. I'll check out the fan and clutch first chance. Thanks for chiming in.
 

·
Supporting Member
Joined
·
4,676 Posts
X2 on the cap. You can have it tested at a local auto parts dealer with the radiator test kit, or borrow the test kit. Thermostat would not cause this type of shutdown issue. Thermostat would show up as high running temps while driving.
 
  • Like
Reactions: GolferSA

·
Premium Member
Joined
·
76 Posts
Discussion Starter · #10 · (Edited)
let's see some pics of the underhood setup with shroud, fan, coolant overflow tank
PO put a cool dude 6 blade stainless fan, no clutch, but a 3" aluminum spacer. Shroud is in great shape, maybe the fan should be deeper in. Replace with clutch fan?

All the fluid from yesterday has drained back into the radiator from the overflow tank. Radiator cap appears to be in like new condition, I'm confused by the markings on it saying "align vent with tube" and arrows point opposite the overflow tube. The only other option would be to turn the cap 180 degrees, but no way to align arrows with tube.
Automotive tire Motor vehicle Automotive design Hood Automotive exterior


Hood Automotive tire Automotive lighting Motor vehicle Automotive design


Tire Automotive tire Motor vehicle Hood Wheel


Motor vehicle White Light Automotive tire Automotive design


Motor vehicle Automotive lighting Automotive tire Steering wheel Hood
 

·
Premium Member
Joined
·
176 Posts
Thanks Tom, it was an NOS GM/AC Delco (RC27) I picked up, shows a 15lb pressure rating. Doesn't mean it isn't faulty though. Think a new cap, thermostat, and fresh coolant are a good idea.
I had similar problem waiting in line at not so fast food Burger King in 90°+ weather. With air on and at idle In gear it started climbing. Changed thmostat, coolent flush.......seems to run cooler by 5 or 10° but it's also cooler outside. We'll see how she does nx week out of town at Gainesville for the NECOA meet and Saturday country cruise.
I think if I get a little more chrome under the hood it should run cool enough then for sure.
Bill
Orlando
 

·
Registered
Joined
·
2,931 Posts
I just had a similar problem on my 2000 Silverado 4.8 Vortec V8 . 1st the water pump went bad after 117K miles . I had the water pump , fan clutch , 180 degree thermostat , radiator hoses & clamps , belts & coolant replaced by my son Scott . He has been a mechanic for over 20 years . It was running good for a week when I got stuck in the drive thru at Taco Bell & it over heated & I was stuck between cars , I had to drive over 2 curbs to get out of line . Once I got back out on the road it cooled down .Turned out the new fan clutch was bad . He swapped it out for a 2nd fan clutch . Seems to working good now . BTW I bought the Silverado new in 1999 .
 

·
Deputy Regional Director, Region 13
Joined
·
6,311 Posts
some thoughts.....

-is that cool dude fan actually pulling air thru at higher rpm's? or are the blades flattening out?
-is that the original water pump? how old?
-when you first start up, take the radiator cap off to look inside. how does the water flow look? maybe a clogged radiator? how old is the radiator?
 

·
Premium Member
Joined
·
76 Posts
Discussion Starter · #14 ·
some thoughts.....

-is that cool dude fan actually pulling air thru at higher rpm's? or are the blades flattening out?
Have not looked, but engine temp is about 195 when driving at 2000rpm, so assume it's mostly working. The problem occurs at idle/shutdown.

-is that the original water pump? how old?
I'd have to look at the build sheet, but it's a fairly recent crate motor our of Denison, Texas.


-when you first start up, take the radiator cap off to look inside. how does the water flow look? maybe a clogged radiator? how old is the radiator?
I'll take a look at water flow, had not done that yet. No idea on the age of the radiator, may be original to the vehicle, which had a 307ci in it. The crate motor is a 325hp/350 bored .030 over... may not be enough radiator, but this boiling over at stop is new.

My guess is that the radiator cap is not holding pressure, allowing coolant to leave the radiator which raises the temp at the sending unit... sounds reasonable, and a simple quick fix to test that theory. Then go from there if the issue remains. Yes?
 

·
Registered
Joined
·
1,164 Posts
The coolant in the radiator will expand and spill into the bottle, then return when cooled down. If you are only running it for a short time you could lose some at stop. Running the motor until everything is hot like a 1 hr ride should have already expanded to the bottle.
Tom
 

·
Deputy Regional Director, Region 13
Joined
·
6,311 Posts
you would THINK it being a recent crate motor all should be good BUT......
-check radiator levels before start up
-check water flow and observe for a few minutes after startup
-how is your lower radiator hose? still strong?
-try testing/replacing your t-stat and radiator cap

I would think your radiator is ok for the size. AFAIK, there really wasn't any variation in radiator installs at the factory
 
1 - 16 of 16 Posts
Top