Erratic Coolant Temperature
Race Director
Joined: Apr 2007
Posts: 11,150
Likes: 890
From: South Western Ontario
) of reverse-rotation pumps for C3's [apparently for serpentine belt systems]. DOOOOHHH!!ONLY the 90's LT1 and LT4 engines are reverse flow and you'd have a very hard time making one of those water pumps work on any GEN1 small block. The mounting on the block is different and there is no way to put pulleys onto it.
The rest of the C4 engines as well as the C5, C6 and C7 engines all flow the same way as the original small block, as in the coolant first flows into the block before going up to the heads. The 90's C4's are hardly late models (recent models) these days.
Race Director
Joined: Oct 2008
Posts: 19,147
Likes: 1,667
From: Long Island
I would also try clipping a good 12 gauge wire from the chassis to the block to make a good ground.
If you have a good Meter you can measure the resistance of the sending unit. Wilcox has a chart where the gauge should be vs resistance.
As a last resort you can "borrow" a thermostat housing with an extra fitting and put a reliable gauge in the fitting.
This will give you a good idea if the water temp is actually changing.
I went bats with a friends 327 a few years ago - until he told me the "HAMMER MECHANIC" he bought the car from "rebuilt the engine himself". There was so much garbage in the water passes ages that they would block the flow. I had to flush the block 4 times to get a full flow. Hopefully the passes ages in the block are clear. I think they probably are.
On thing I found - a while ago. Check to see if the temp ending unit is bottoming out in the motor. I found some of the replacements too long and hit the block.
Just some thoughts....
If you have a good Meter you can measure the resistance of the sending unit. Wilcox has a chart where the gauge should be vs resistance.
As a last resort you can "borrow" a thermostat housing with an extra fitting and put a reliable gauge in the fitting.
This will give you a good idea if the water temp is actually changing.
I went bats with a friends 327 a few years ago - until he told me the "HAMMER MECHANIC" he bought the car from "rebuilt the engine himself". There was so much garbage in the water passes ages that they would block the flow. I had to flush the block 4 times to get a full flow. Hopefully the passes ages in the block are clear. I think they probably are.
On thing I found - a while ago. Check to see if the temp ending unit is bottoming out in the motor. I found some of the replacements too long and hit the block.
Just some thoughts....
Racer
Joined: Apr 2016
Posts: 493
Likes: 65
Help me to understand, the pumps are all reverse flow, from the factory? Did they start off that way, or was it changed after the first one came out? I'm asking because I'm not sure what is flow, and reverse flow now.
The coolant still flows in the same direction, no matter which pump is used, or is the reverse flow actually go backwards from the regular flow?
Thread Starter
Heel & Toe
Joined: Jan 2014
Posts: 22
Likes: 1
Hi All,
Thanks for the many replies, I'll be working on the following tasks this weekend.
1. I will remove the thermostat and test for correct temperature operation.
2. I will remove and replace the water pump after removing the bypass plug from the block.
3. I will conduct resistance tests to determine if the wiring has an intermittent fault.
I don't have access to a infrared gun, so that will have to wait a bit, I'll let you know how it goes soon.
John
Thanks for the many replies, I'll be working on the following tasks this weekend.
1. I will remove the thermostat and test for correct temperature operation.
2. I will remove and replace the water pump after removing the bypass plug from the block.
3. I will conduct resistance tests to determine if the wiring has an intermittent fault.
I don't have access to a infrared gun, so that will have to wait a bit, I'll let you know how it goes soon.
John
Team Owner
Joined: Jul 1999
Posts: 65,492
Likes: 230
From: Orange Park Florida
OP, check you don't have a leaking intake mani gasket, maybe even a head gasket.....make DAMN sure you don't have any coolant into the cylinders....get engine hot, and pull the plugs, especially on the ends...or first two/last two on each bank.....Check they are tight.....
Don't ask.....
Don't ask.....
Last edited by mrvette; Feb 4, 2017 at 09:26 PM.
