WTF did I do on this water pump job?!?!?!

[rjd2]

So my nicely running and driving '76 2002 with stock motor and either 46k or 146k on it, I always had an oil leak at the timing chain cover. It wasnt a big deal until 2023, when it got worse and more annoying. Mind you, I had a stock radiator, silicone hoses, and the temperature management was phenomenal. I never once saw my temp past 2 o clock, even if i ran it at 5k RPM in the summer heat. So I buckled down and pulled the timing chain, and did the gaskets, water pump, and new walloth and nesch radiator "while i'm in there". I get everything buttoned up and am feeling great about the utter lack of leaks, and the preventative maintenance. But now I have a new problem; my water temp just wants to make a beeline for the red as soon as the car heats up. immediately. can anyone take a look at the readings I shot today, and help me make sense of this? 160-ish all around on the top end of the engine, and....60 at the output side of the water pump. the belt is spinning the water pump properly. I'm stumped. I don't see how I could have had any blockage in the lower hoses; I had the whole system apart and everything looked clean as a whistle. thanks for any advice....

[Leucadian]

Have you burped the engine to remove any air bubbles in the system?

[tzei]

New water pump? Put the old one back?

[jimk]

Try connecting the temperature sensor wire to the sensor!

[tech71]

Might be time to install a secondary ground on backside of temp gauge.

A fan shroud wouldn't hurt either.

Edited March 28 by tech71

['76mintgrün'02]

You will not get accurate readings from the IR gun unless it is relatively close to all the surfaces you are measuring.  The laser pointer is misleading.  The IR gun's 'focus' is cone shaped.  Try measuring the temperature of the bottom hose from below, so the gun is right up close to it. 

 

2 hours ago, rjd2 said:

 

[TobyB]

+1 for burping- the stock thermostat can get an air bubble around the wax pellet canister,

and that keeps it from opening in a timely manner.   

 

Also +1 for not trusting the IR gun until you've gotten familiar with them.

 

t

 

[bmdubl02]

How does one burp the cooling system?

[Leucadian]

15 minutes ago, bmdubl02 said:

How does one burp the cooling system?

 

Lay the car upside down across your lap and give 3-4 hard raps between the two front wheels, that should do it.

 

Sorry, couldn't resist.  

 

Easiest way is to park on an incline (rear wheels lower than front wheels) with the engine running and the radiator cap off.  Let the engine come up to temp and let it idle for a few minutes.  Then throw the cap back on and go give it a drive.

Edited March 29 by Leucadian

[Son of Marty]

You'll need to set your heater valve to full hot before trying the above.

[John76]

41 minutes ago, TobyB said:

+1 for not trusting the IR gun until you've gotten familiar with them.

Those IR guns can show huge errors if not used correctly.

Most common mistake is thinking the laser dot is showing where the temperature is coming from.... WRONG!

Look for a distance/spot size ratio on the IR device you are using. It's also listed in the spec sheet.

Most low-cost IR guns have an 8:1 distance /spot ratio. This means at a distance of 8" from the target, the area being measured is 1" diameter. At 16 inches, the spot is 2". 24"distance is 3" target etc., etc. The laser dot only identifies the middle of the target spot.

Second common mistake is trying to measure the temp of a shiny surface and compare it to a dull surface at exactly the same temperature. Example: Pointing the IR gun to your aluminum water pump, head, or water divider and seeing the temperature much cooler than the black (or blue) coolant hose connected to them. Dull, dirty, greasy, rusted, or painted surfaces are ideal targets for IR guns. Nothing shiny (chrome, aluminum, brass, copper, etc.).

Been there, done that for 40+ years...ask me how I know. 

John

IR Smart ... kinda

[rjd2]

thanks folks. I THOUGHT I had successfully burped the system, in that i ran the car with the cap off after filling, seeing a dip in coolant level, but i'll raise the front end on jack stands and repeat the process. appreciate the help!

[conkitchen]

 

[stephers]

Just loosen off the temp sender, once coolant starts coming out of there , it is pretty much bled.     Run for a bit, it will push some coolant out first,, then will settle down and you may have to add just a little bit

[rjd2]

Well, I'm stumped here folks. The saga continues....here's where I'm at after a morning of work:

-the IR temp reader I have has a margin of error in the range of 2-3% when fluctuating the physical range from 2" to 15" or so. it's something, but a rounding error, for my purposes.

 

While I had burped the system when I filled it, and then consequently replaced the temp sending unit( and getting coolant to gush at that location), I additionally got the front end WAY up in the air today, removed the cap, and got the car to temp. I was able to get the gauge up to around 1:30pm, not touching the red, but about 3/4 of the way up. sitting on the throttle, I couldn't get it higher. FYI, the coolant level did not budge.

 

I dropped the car, put the cap on and drove it. within 5 blocks, the gauge is touching the red. I got back to the shop, shot temperatures, and made this diagram. Please take a look, and let me know what you think. I recognize that technically, 177F on the intake manifold is not a temperature that I necessarily need to lose my shit over, the bottom line is that I don't think I'm ready to resign myself to driving a car with the temp gauge in the red and calculating that as "oh yea that's just normal lets keep driving". Mind you, relative to the gauges and the wiring, NOTHING changed during the water pump job.

 

Do the below numbers look "right" to you? (the two larger coolant hoses at the water neck read around 160)