# Help on Cooling Issues



## peahrens (Jun 7, 2010)

Hi all. Yesterday I got back the '66 389 tripower after cam / lifter replacement. The shop broke it in for 30 minutes, then drove it another 30 or so. I took it for a drive and have 2 issues related to the cooling system. What's changed is a new water pump, new thermostat (I don't have a record of which one I bought but might find out at Auto Zone). Also, replaced the radiator to a new 4-core US Radiator from Ames (since it used to run pretty warm in hottest weather). It's 15-1/2", not A/C car. Plus, I put a shorter(1" instead of 1-1/2") fan spacer to reduce water pump risk. 

So here's the issues. First, the temp gauge (and 80F air temp) makes me think it's running significantly hotter than before. The gauge has marks at 100/180/245, with ticks in between (140 & 212). The gauge (at 40-55mph or so) was hanging around 230+F. I believe it was more like 190-200F in similar conditions. The coolant is 50/50 Prestone/water. I did not change the temp sending unit. The fan is a 17-1/2" 7 blade GM 3947772, with about 2" pitch, which Googles as one used on things like certain Camaros. It's got a fan clutch, which "feels" normal then turned by hand. It's installed facing the same way (blade holders on the back), but of course 1/2" further back. I have a molded (fiberglass) shround, which has a 20" opening. So, I'm concerned it may be running enough hotter that it may overheat on 95+F days.

The 2nd issue is the fan/clutch/spacer are wobbling very noticeably. Undoubtedly enough to hurt the water pump quickly, I'd think. Don't know if the new spacer faces are not square (I'd think unlikely), the clutch shaft is bent (don't see how), it's inslalled cocked somehow, etc. Or could the "new" (rebuilt) water pump have an unsquare front flange?? 

I'm wondering what to do first, plus what the best long term solutions are. It gets hot here so I'd like good cooling. Should I try another type fan? I don't want to add an electric auxiliary fan. Also, some catalogs say don't use a clutch with a fan spacer, but don't I want the fan to reach at least partially into the shroud to pull air better? 

Maybe it's a simple as correcting whatever is wrong about the wobbling, plus putting on a 1-1/2" spacer again???

I can't just drive back down to the shop until I work out the fuel drips at the carb fittings...an important side issue.

Any comments are much appreciated, especially before I take things apart.


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## freethinker (Nov 14, 2009)

peahrens said:


> Hi all. Yesterday I got back the '66 389 tripower after cam / lifter replacement. The shop broke it in for 30 minutes, then drove it another 30 or so. I took it for a drive and have 2 issues related to the cooling system. What's changed is a new water pump, new thermostat (I don't have a record of which one I bought but might find out at Auto Zone). Also, replaced the radiator to a new 4-core US Radiator from Ames (since it used to run pretty warm in hottest weather). It's 15-1/2", not A/C car. Plus, I put a shorter(1" instead of 1-1/2") fan spacer to reduce water pump risk.
> 
> So here's the issues. First, the temp gauge (and 80F air temp) makes me think it's running significantly hotter than before. The gauge has marks at 100/180/245, with ticks in between (140 & 212). The gauge (at 40-55mph or so) was hanging around 230+F. I believe it was more like 190-200F in similar conditions. The coolant is 50/50 Prestone/water. I did not change the temp sending unit. The fan is a 17-1/2" 7 blade GM 3947772, with about 2" pitch, which Googles as one used on things like certain Camaros. It's got a fan clutch, which "feels" normal then turned by hand. It's installed facing the same way (blade holders on the back), but of course 1/2" further back. I have a molded (fiberglass) shround, which has a 20" opening. So, I'm concerned it may be running enough hotter that it may overheat on 95+F days.
> 
> ...


but don't I want the fan to reach at least partially into the shroud to pull air better?yes

how much did you drive it after the cam change. maybe there is an air lock or it isnt full of water. how about the lower hose? is it collapsing?
if it gets that hot just driving 55 mph i doubt its the fan. that would show up sitting still. forced air from driving should cool it at that speed.
maybe its the gauge. the thermostat should be open and have no effect at that temp.the radiator is new. the fan is more than enough. that leaves the water pump/engine. for sure if the pump shaft is bent it needs to be replaced.
i have a 66 tripower and i dont even run a shroud and it doesnt overheat.

i have read about a modification you can make to the water pump backing plate to improve cooling but i have never had to do it.


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## peahrens (Jun 7, 2010)

I talked to the mechanic today and on the temp issue he wants to use his digital thermomenter to get an idea of what the temp is doing. he thinks it may not be overheating. we'll see next week.


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## geeteeohguy (Feb 2, 2008)

You should have an 18" fan for a GTO and it should be half in and half out of the shroud. You should not run a spacer on a fan clutch. The clutch IS the spacer. I suspect the new water pump has a stamped impellor and/or is not clearnaced to the separator plates correctly. Proper clearance of the water pump impellor blades to the seperator plate assembly is CRITICAL. There is much info about this on line, particularly on the pyforumsonline, under "cooling tech". There is a 'sticky" on this forum about the issue. Another thing: was your sending unit changed? New sending units tend to make the Pontiac gauge read hot, if factory gauge equipped. Lectric Motive has the right one. The ignition timing has to be checked, as does the air/fuel mixture, too. All can lead to a hot engine.


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## freethinker (Nov 14, 2009)

peahrens said:


> I talked to the mechanic today and on the temp issue he wants to use his digital thermomenter to get an idea of what the temp is doing. he thinks it may not be overheating. we'll see next week.


good idea. i suspect the gauge also.


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## peahrens (Jun 7, 2010)

it's the same temp sending unit from 18 yrs ago (probably new then). the mechanic said he advanced the timing more than spec (I think because the cam is a bit hotter than OEM)...would that tend toward running hotter? I have a light to check the timing (vs 6-deg BTDC spec) but can't figure out the timing marks on the pulley yet.


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## geeteeohguy (Feb 2, 2008)

You say the water pump was changed. Again, you need to verify the clearance. It's vital, and this could well be your problem.


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## peahrens (Jun 7, 2010)

thanks. I'll look over the references you point out on the clearances. I just let it run awhile at 1100 rpm and it stayed below the 212F mark. And the timing is close to the 6 degrees BTDC. I'll have to get some more driving dat and investigate your leads to see the extent of the problem. I'm not sure whether the fan shaft wobbles or not...wil get a 2nd opinion.


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## peahrens (Jun 7, 2010)

Well, I've looked a bit at the info on PY Forums Online. I need to digest it more as at this point I'm pretty confused. The threads seems to be between folks who know lots about the issues and alot of it's going over my head. 

I need to talk to my mechanic about the pump he installed. Would he have reused old divider plates or do new ones come with the rebuilt pump (I wouldn't think so)? I haven't figured out the specifics on divider plate clearances from the threads. How do I figure out whether my pump & plate installation is ok (take it apart)? 

Did I read the dates right on the PY Forum threads that just the past few days some folks met with a pump company (Cardone) about the fact that many pumps are built wrong or poorly. If my rebuilt pump turns out to be bad, what would the best approach be to make things "good"? Buy a new 8-bolt pump from a specific manufacturer and new divider plates and make sure I install them per some clearance specs? Should I buy an Evans pump, a Flow Coolers pump, wait for a redesigned Cardone pump, etc??? Can Ames advise me with current best info? Or can I get someone who understands all this to call me?

If it runs hot, my bias will be to put in the best cooling pump, new (if better) divider plates, and ensure I understand the clearance directions (the manual gives no details). 

Again, commentsand/ or directions to the best info source appreciated.


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## 66tempestGT (Nov 28, 2009)

the way i understand it you can bend the plate to make any pump work efficiently.


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## peahrens (Jun 7, 2010)

1. Overall cooling problem: I got the old pump from the shop, in a Cardone box (the replacement). But I won't know what the impeller looks like until I pull the pump. The mechanic said the divider plates were pitted / corroded a bit. He unfortunately did not note the clearance from the impeller to the "internal housing" (rear divider) plate with the gasket. So, I think I'll order the new divider plates so I can then pull the pump. Haven't decided about whether to adjust plates to the suggested 0.1" clearance from existing pump or await a new Cardone pump with correctly aligned impeller placement on shaft. Maybe will wait to see how big the impeller is in the current pump. I ran it yesterday (temp in the 60's) and it ran under the 212F mark. I want it cooling well by summer so by then I will at least pull the pump and adjust divider plates.
2. Fan shaft wobble problem. I showed the problem to several mechanics and there's definitely something wrong here. It looks like the pulley is running square (and presumably the pump baseplate it's attached to), but the 1" spacer and the fan clutch (engine side) shaft wobble decidedly (too much). Also, a couple of the fan blades are not in line with each other. So, assuming our eyeball viewing is correct and the water pump baseplate and belt pulleys are square, the possibilities include an unsquare (aluminum) fan spacer, an unsquare fan clutch baseplate casting, or an unbalanced effect from the fan that makes the assembly wobble even if square. Hard to believe someone sells an unsquare fan spacer. Also hard to believe the fan clutch (cast) shaft is unsquare. BTW, I used the fan spacer (with the clutch) since the fan is about 1/2 in the shroud that way. The 1-1/2" clutch fan mount to baseplate alone is not long enough my mechanic says. Could the fan clutch be screwed up to whare it's inducing the wobble (it feels tight when moved by hand)? Should the fan tips be in line or not necessarily? The 7-blade fan has odd spacing of the blades, so I don't know for sure whether the blades are not intended to be on the same exact plane. Also, which way should the fan face...with the baseplate forward (blades to the rear) or the baseplate on the engine side (blades to the front). I've got it with the blades in the front (baseplate rearward). If the fan blades should be in plane, should I bend the baseplate "leaves"? They are fairly stiff. I do see an 18" 7-blade on Ebay that is advertised for GTO (and others) , but don't know if it has better specs (e.g., my current 2" pitch). The sledge hammer would be a new fan, clutch and spacer but would like your comments before disassembling or ordering parts.

Again, thanks...you guys are extremely helpful.


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## freethinker (Nov 14, 2009)

peahrens said:


> 1. Overall cooling problem: I got the old pump from the shop, in a Cardone box (the replacement). But I won't know what the impeller looks like until I pull the pump. The mechanic said the divider plates were pitted / corroded a bit. He unfortunately did not note the clearance from the impeller to the "internal housing" (rear divider) plate with the gasket. So, I think I'll order the new divider plates so I can then pull the pump. Haven't decided about whether to adjust plates to the suggested 0.1" clearance from existing pump or await a new Cardone pump with correctly aligned impeller placement on shaft. Maybe will wait to see how big the impeller is in the current pump. I ran it yesterday (temp in the 60's) and it ran under the 212F mark. I want it cooling well by summer so by then I will at least pull the pump and adjust divider plates.
> 2. Fan shaft wobble problem. I showed the problem to several mechanics and there's definitely something wrong here. It looks like the pulley is running square (and presumably the pump baseplate it's attached to), but the 1" spacer and the fan clutch (engine side) shaft wobble decidedly (too much). Also, a couple of the fan blades are not in line with each other. So, assuming our eyeball viewing is correct and the water pump baseplate and belt pulleys are square, the possibilities include an unsquare (aluminum) fan spacer, an unsquare fan clutch baseplate casting, or an unbalanced effect from the fan that makes the assembly wobble even if square. Hard to believe someone sells an unsquare fan spacer. Also hard to believe the fan clutch (cast) shaft is unsquare. BTW, I used the fan spacer (with the clutch) since the fan is about 1/2 in the shroud that way. The 1-1/2" clutch fan mount to baseplate alone is not long enough my mechanic says. Could the fan clutch be screwed up to whare it's inducing the wobble (it feels tight when moved by hand)? Should the fan tips be in line or not necessarily? The 7-blade fan has odd spacing of the blades, so I don't know for sure whether the blades are not intended to be on the same exact plane. Also, which way should the fan face...with the baseplate forward (blades to the rear) or the baseplate on the engine side (blades to the front). I've got it with the blades in the front (baseplate rearward). If the fan blades should be in plane, should I bend the baseplate "leaves"? They are fairly stiff. I do see an 18" 7-blade on Ebay that is advertised for GTO (and others) , but don't know if it has better specs (e.g., my current 2" pitch). The sledge hammer would be a new fan, clutch and spacer but would like your comments before disassembling or ordering parts.
> 
> Again, thanks...you guys are extremely helpful.


lots of questions. you are going a lot of ways at once. since its a known problem with the pump i would start there make sure thats correct. just installing new divider plates wont necessarily fix the problem. thay have to be bent to correct the adjustment. 
the fan can only go 1 way. it has to suck air through the radiator.


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## peahrens (Jun 7, 2010)

Fan wobble solved today. Removed the fan / clutch / spacer. A buddy measured the 1" spacer and it varied 0.045" between the faces from one side to the other (shorter along the axis on one side than the other).Add the 1-1/2" length of the clutch and the additional length of the clutch (past the fan) and it sure dod wobble! He put it in the lathe and turned it to pretty darn parallel fac to face. Reinstalled and it looks normal (good) when turning 1000 rpm or so. Hooray! 

Will still have to address running warm...pull pupm and adjust divider plate clearance, check thermostat, maybe get into timing issues.


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## GTO JUDGE (May 14, 2005)

peahrens said:


> Fan wobble solved today. Removed the fan / clutch / spacer. A buddy measured the 1" spacer and it varied 0.045" between the faces from one side to the other (shorter along the axis on one side than the other).Add the 1-1/2" length of the clutch and the additional length of the clutch (past the fan) and it sure dod wobble! He put it in the lathe and turned it to pretty darn parallel fac to face. Reinstalled and it looks normal (good) when turning 1000 rpm or so. Hooray!
> 
> Will still have to address running warm...pull pupm and adjust divider plate clearance, check thermostat, maybe get into timing issues.


Using Waterwetter? I have a 160* highflow thermostat and use WaterWetter. My heater throws plenty of heat. Car in the summer runs 180-185. 170* or so in cooler weather.

http://www.redlineoil.com/product.aspx?pid=74&pcid=10


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## 1625Goat (Feb 25, 2011)

I installed a FlowKooler WP on my 68 GTO and it has a plate welded to the propellers to increase water flow and cooling. You still need to install the divided plates or the water will just cavitate. I also installed a 160 thermastat. While it's not hot yet here it's been up to low 60s. My temp goes to 160 and once the therm opens it drops just below. I let it idle for 40 mins & no change in temp.


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