# Is it possible to overtighen a water pump?



## GFT 12:17 (Jul 26, 2014)

I was reinstalling my water pump and once I started filling the radiator with coolant I noticed a small leak. Coolant was bubbling out near a bolt and I notice a hair line crack. Could I have over tightened it and cracked it? Once the engine warms up does the gasket "melt" and form a seal? 

My water pump has a stamped impeller with two divider plates. Are the cast iron impellers better?


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## GFT 12:17 (Jul 26, 2014)

It's cracked... I just took a picture, but unable to post it. Is this terminal?


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## 67Twistytee (Feb 24, 2014)

It's not clear based on your description as to where you see a crack. The timing cover is aluminum so you do not need to over torque the water pump bolts or you could damage the cover. Is it the cover that cracked or the actual water pump itself? Sounds like you now need to replace either the pump or timing cover. Can you try to repost a photo?

Coolant can sometimes get past a bolt head if you didn't get all of the old gasket material or sealant removed between the two mating surfaces. I usually use a thin razor to scrap off the old gasket and then lightly sand before applying sealant and a new gasket. As to your other question, many people successfully use pumps with stamped impellars, especially if the rest of the cooling system is in good order. But the consensus is the original cast impellars (not shaved rebuilds) lead to better fit of the divider plates and less likelihood of coolant cavitation. Some of the newer cast replacements are hit or miss. I've had good luck with Gates.


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## Goat Roper (Oct 28, 2014)

Yes it is very possible to over torque the water pump bolts, the last ham fist that replaced my pump stripped out the timing cover and the threads came out with the bolts.
The torque is 15 ft. lbs.
Start at 5 with a criss cross pattern then 10 and finish at 15.
If you don't have the factory service manual get one and read up on each thing before you begin.
It will save you money and you will avoid most of the WTF! moments.


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## geeteeohguy (Feb 2, 2008)

What these gents said, and yes, a cast impeller pump is superior to a stamped impeller pump. Pretty hard to crack a pump, pretty easy to damage a timing cover. And no, the crack won't heal itself. If it's the cover it needs to be repaired or replaced.


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## GFT 12:17 (Jul 26, 2014)

I have replaced my water pump, reduced the distance between my plates and impeller (to a level I thought is acceptable). Ran the car and the engine temp got to approx 195 degrees. Turn off the car, the temp climbs and watched fluid leak from the relief hose at the radiator cap. I also got a new radiator cap and thermostat. Radiator has been recored but don't have a fan shroud as I couldn't get one to fit correctly (not the original motor). Do I need to adjust my plates more? With the engine running and the radiator cap off, should I see fluid circulating past the opening? If the fluid isn't moving, is that because my plate isn't close enough to the impeller? Thanks. Tim


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## PontiacJim (Dec 29, 2012)

GFT 12:17 said:


> I have replaced my water pump, reduced the distance between my plates and impeller (to a level I thought is acceptable). Ran the car and the engine temp got to approx 195 degrees. Turn off the car, the temp climbs and watched fluid leak from the relief hose at the radiator cap. I also got a new radiator cap and thermostat. Radiator has been recored but don't have a fan shroud as I couldn't get one to fit correctly (not the original motor). Do I need to adjust my plates more? With the engine running and the radiator cap off, should I see fluid circulating past the opening? If the fluid isn't moving, is that because my plate isn't close enough to the impeller? Thanks. Tim



Your thermostat has gone bad -even if you just put in a new one. Sometimes the "foreign stuff" just goes bad from the get-go. 

Here is a little trick I do with my thermostats. I drill two 1/8" holes through the flat area next to the center (not too far to the outside so as you will put the hole over the recess where the t-stat fits into the hole on the intake.) What this does is allows any air that might be in your system to escape through these holes. If you get air trapped in your cooling system, it can cause overheating problems, so this eliminates that from the beginning.

But, all said, replace that thermostat because it is not opening I like a 160 degree t-stat for personal reasons, but the 180 will work just fine for a stack engine. I would NOT run the 195.:thumbsup:


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## PontiacJim (Dec 29, 2012)

Also make sure your upper and lower radiator hoses are not collapsing cutting off the circulation. This can sometimes happen if you use hoses that do not have the springs in them to keep the hoses expanded -not always -but it can happen and have had it happen depending on type/brand of hose.


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## 67Twistytee (Feb 24, 2014)

^^What Jim said.

A 180 T stat should be fine for most stock engine applications. I run a 160 in the summer just for the extra safety margin and early coolant flow. I also like the high flow stats that follow the old Robertshaw design. Mr. Gasket (4364) or EMP/Stewart 301 are two that work well and have the 3 hole bypass which serves the same function Jim mentions regarding drilling the holes. 

Most lower radiator hoses no longer come with springs. Some owners will take the old one out and install with new hose. You can check to see if the lower hose is collapsing when you rev the throttle, but if you're using good hoses this is normally not an issue.

And yes you should see good coolant flow across the radiator opening when your thermostat is open and you're revving the engine. Lack of flow and bubbling from the overflow hose could be a number of issues aside from the pump (like collapsing hoses, radiator restriction, improper timing causing over heating, etc.). The plate clearance issue can reduce flow, but it should still be present when the t-stat is open and you look down the radiator neck. Keep trouble shooting and post your results.

Good luck.


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## GFT 12:17 (Jul 26, 2014)

Replaced the t-stat with a new 160 degrees (and drilled two 1/8" holes). Let the engine warm up, with the engine running and with an infrared gun, checked the temp at the neck where the t-stat sits, 175. Checked the temp of the upper hose to the radiator 160, checked the temp of the lower hose of the radiator, 158. Turned off the car and it began to spill fluid from the line attached to the radiator cap. Could it be my radiator? My engine is now "dieseling" once I turn it off.


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## 67Twistytee (Feb 24, 2014)

Sounds like you may have over filled the coolant. When system is full (cold) you want it 1" below the radiator cap neck so you have room for expansion when it gets hot. Coolant capacity with heater core on a 389 is 20 quarts. Normal for 1-2 gallons to remain in block so you can't completely drain without removing the freeze plugs. 

When it was running did you blip the throttle and look for coolant movement past the radiator cap? If you don't see good flow it's possible you have a blockage in the radiator although not likely as you said it's been re-cored. 

Dieseling is probably unrelated. Usually caused by the throttle plates not fully closing. Check the throttle linkage to make sure it's not sticking. Also check the choke. Advanced timing or idle mixture screw settings can also cause this. If it doesn't go away, your primary throttle shaft bushings may need to be replaced.


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## geeteeohguy (Feb 2, 2008)

What Twistee says. Overfilled radiator. My advice would be to lower the coolant level or retrofit a simple overflow can. (which is a great idea, anyway)


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## chuckha62 (Apr 5, 2010)

Along with what these gents have said, I would encourage you to find a shroud that fits. The benefits of a properly fitting and spaced shroud cannot be overstated. 

I'm not sure if your car was equipped, but mine was... With an anti-diesel solenoid. If properly adjusted, it works very well and there's no real down side to keeping it in place, other than it clutters up the throttle side of the carb.

Chuck


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## GFT 12:17 (Jul 26, 2014)

Great feedback. Thank you. I will keep after it and let you know the results. I was thinking the dieseling may have been some bad gas... I'm buy non-ethanol gas and wonder if the octane wasn't as high as advertised.

Any suggestions on how to find a shroud the fits. I purchased the typical pre-drilled plastic shroud but it just didn't seem to fit/line up with the fan and radiator.


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## PontiacJim (Dec 29, 2012)

GFT 12:17 said:


> Replaced the t-stat with a new 160 degrees (and drilled two 1/8" holes). Let the engine warm up, with the engine running and with an infrared gun, checked the temp at the neck where the t-stat sits, 175. Checked the temp of the upper hose to the radiator 160, checked the temp of the lower hose of the radiator, 158. Turned off the car and it began to spill fluid from the line attached to the radiator cap. Could it be my radiator? My engine is now "dieseling" once I turn it off.



Temps all look good, no problems there. The line attached to the radiator cap is the small one? That is the overflow tube. You will get some overflow which can be very normal when you first fill your radiator. When you shut the engine down, heat soaks into the coolant and like all things, heat makes the coolant expand and overflow. My experience is that it may do this a few times until the coolant level "normalizes" from the heating/cooling of the fluid. Seeing all your temps are good, I would guess it too be the coolant is overfilled. If you fill it right to the top, its usually too high. After some time of cycling, take a look when it is cool and see where the level is. It will probably be 1 to 1 1/2" (possibly more depending on radiator type) down from the top. The only time I worry is if I can see the radiator tubes and no coolant covering them.

You could also still have an air pocket in the system that has to work itself out. Run the engine and also rev it up to get the fluid moving about. More coolant may even leak out when you rev it up - again, expansion. So run your car a few times, cycle it, and each time it cools give the radiator level a check. Do not add any coolant unless it appears too low and is not covering the internal cooling tubes. 

"Dieseling" is BAD for your engine. You can do major damage. Dieseling can be brought on by a number of things.

1. Todays blended fuels is one of them. 
2. If your idle RPM's are too high, this is the main cause because your throttle blades at the base of the carb are slightly cracked open and the engine continues to draw air/fuel, however slight, and keeps running even with the key off. (Pontiac addressed this in later engines by installing an electric idle solenoid that was energized to set carb idle and when the key was shut off, completely shut the throttle blades tight as the electric solenoid piston fully retracted.) 
3. You timing may need adjustment - off the top of my head it may need to be retarded?
4. Make sure no vacuum leaks.
5. Make sure your carb is not leaking internally, ie bad gasket or bad float level setting.

IF the engine begins to diesel, IMMEDIATELY turn the key back on so it runs. Then put the car in Drive if automatic, and then shut the key off while still in Drive. If a manual trans, put the trans in 4th gear, turn the key off and release the clutch to stall the engine. Do what it takes to avoid dieseling at all costs, but you will have to fix this problem or risk internal damage to the engine that could be major.:thumbsup:


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## GFT 12:17 (Jul 26, 2014)

Got the appropriate level of coolant in the radiator and ran the engine with the radiator cap off. Checking the temp with my infrared gun, it was interesting to see the coolant start to flow across the radiator opening once the temp hit 160 and the t-stat opened. The coolant was flowing like a river, which told me my divider plates where a good distance from the water pump impeller. Sealed up the radiator and when for a drive, no issues. Went for a 30 mile drive this morning, no issues. Temps were perfect.

Filled up the tank with 93 octane and haven't had any dieseling issue.

Thanks again for the help!

Tim


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## PontiacJim (Dec 29, 2012)

GFT 12:17 said:


> Got the appropriate level of coolant in the radiator and ran the engine with the radiator cap off. Checking the temp with my infrared gun, it was interesting to see the coolant start to flow across the radiator opening once the temp hit 160 and the t-stat opened. The coolant was flowing like a river, which told me my divider plates where a good distance from the water pump impeller. Sealed up the radiator and when for a drive, no issues. Went for a 30 mile drive this morning, no issues. Temps were perfect.
> 
> Filled up the tank with 93 octane and haven't had any dieseling issue.
> 
> ...


EXCELLENT, you got your summer driver, and your worries are now behind you! :cheers


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