[Slick]

Blackwood Goat,

Before the repair, the motor would overheat whenever in traffic. I couldn't even run the A/C. I wish I could say that I changed nothing else, but unfortunately I changed lots, even the car (but both were A bodies). The last time I used this motor was 8 years ago. This year, I needed a temporary motor to get the GTO running again and figured this would work. Since there was already a heating problem I knew that it needed to be addressed. I was already using a 4-row radiator, 19.5" factory flex fan, etc.

When putting the GTO on the road, I found a wiped cam (old solid lifter, but pretty mild) cam. The car before, also an A body, had manifolds, 2.5" duals, T350 with 12" converter, separate trans cooler, Q-Jet, iron intake, etc.

Now, back in the 71, the car has 1-5/8" headers, 2.5" duals, cooling as mentioned previously (same fan actually), T400, 10" converter, Summit 2802 cam, iron intake, Q-Jet, etc. Same 7K3 heads and short block as before. Since the same front cover was on the motor from its overheating days, it was easy enough to check and sure enough there was a sheetmetal impeller pump with God knows how much clearance, certainly over 0.150".

The change was so drastic, I know the proper pump impeller and clearance did the trick. The motor used to heat up badly before even when the cam was new and not wiped.

Stuart

[mikeb]

Originally Posted by 1967Tempest

It is way cool that your daughter is involved. Did you try the easy, and free stuff?? Making sure the lower hose isn't collapsing, upper hose has no air etc...


Dave

Hoses are brand new, I hope that that are not collapsing I think we have tried all of the cheap stuff like checking the timing, burping air out, hammering down the divider, swapping the t-stat, etc. Carb is a loaner until I get my q-jet rebuilt, it smells rich and will water your eyes so i'm pretty sure it's not lean. I have no idea about the mixture though.

Next steps are to try the ac delco sending unit, double check the temp with a meat thermometer, and try to find a water pump with the right cast impeller to replace the flowkooler. I should know more by the end of next weekend, and i'll report back here then.

Originally Posted by lester

I have a 75 400 in my 79 t/a . use the snding unit in the motor for what year and motor that was in your car. so it works with the gage in the car. i run a 160 stat now to. i had the 190 . then 180. i was over 220 with them. put the 160 t-stat in and I'm at 175 at 65mph all day long and 165 in town. fyi never shut down the motor when your braking in a cam. mine was at 240 at 2 grand and I held the water hose on the rad to bring it down to 220 and let it run for a 1/2hr. changing the rpm every 5 min.

I have a 180 in there now. Might try a 160. The car was sitting on jackstands in the garage so I could not easily move it out in the driveway to put water on it (and the brakes aren't 100% yet either), so we shut it down when it went over 220. I've read where this is ok during cam breakin, I guess we'll find out.

Some on this thread have questioned their sending unit. I'm doing the same, when I turn the key on the gauge will jump up to 220 (if the engine is hot), and then without the engine running it will "creep" up to 240. Seems fishy to me.

[Old Goat 67]

I have one of these type of thermometers.
Paid a lot more than this. You might want to try one.
Worth their weight in gold for all sorts of tests, car and home.

http://www.harborfreight.com/cpi/cta...emnumber=96451

[mikeb]

Originally Posted by Old Goat 67

I have one of these type of thermometers.
Paid a lot more than this. You might want to try one.
Worth their weight in gold for all sorts of tests, car and home.

http://www.harborfreight.com/cpi/cta...emnumber=96451

my favorite place! harbor freight!

[Blackwood Goat]

Originally Posted by mikeb

Hoses are brand new, I hope that that are not collapsing I think we have tried all of the cheap stuff like checking the timing, burping air out, hammering down the divider, swapping the t-stat, etc. Carb is a loaner until I get my q-jet rebuilt, it smells rich and will water your eyes so i'm pretty sure it's not lean. I have no idea about the mixture though.

Next steps are to try the ac delco sending unit, double check the temp with a meat thermometer, and try to find a water pump with the right cast impeller to replace the flowkooler. I should know more by the end of next weekend, and i'll report back here then.



I have a 180 in there now. Might try a 160. The car was sitting on jackstands in the garage so I could not easily move it out in the driveway to put water on it (and the brakes aren't 100% yet either), so we shut it down when it went over 220. I've read where this is ok during cam breakin, I guess we'll find out.

Some on this thread have questioned their sending unit. I'm doing the same, when I turn the key on the gauge will jump up to 220 (if the engine is hot), and then without the engine running it will "creep" up to 240. Seems fishy to me.

Mike
Before involving yourself with the sending unit you may want to invest in a Infrared Temperature Gun. You can get a decent one for around $50.00. They have a mutitude of uses. Rich

[Norwood]

Originally Posted by mikeb

my favorite place! harbor freight!

Harbor "Fright" the home of throw away tools.....

[mikeb]

Originally Posted by Blackwood Goat

Mike
Before involving yourself with the sending unit you may want to invest in a Infrared Temperature Gun. You can get a decent one for around $50.00. They have a mutitude of uses. Rich

The sending unit is already on the way. I'll investigate the infrared temp gun.

[mikeb]

WooHoo!!! Found a water pump at kragan with the cast impeller and the "good" style vanes on the first try. Gonna try it tomorrow. Pics to follow.

[lazlo]

Medina, Oh. Carquest parts store ordered all three water pumps in the warehouse so we could check them all for a cast impeller. One was cast, the other two were stamped... So I appreciate that effort.

Hammered the plate down to where it is almost touching then put the gasket behind it & installed. 160 degree thermostat, and a Pontiac correct flex fan, shroud, and 4 core radiator.

Put the first 100 miles on the 2nd motor rebuild tonight and the temps never went over 175, even in traffic...

I think it works & I appreciate the information gleaned from this thread.

Ref the infared temp sensors... Summit has them for about $35.00.. Bought one early this summer and use / play with it all the time.. laz

[mikeb]

Here are some pics of what we swapped out today. The water neck has become a leaky place, so we didn't start the car today while we await the permatex to cure on it. I thought i'd go ahead and post the pics. I have high hopes for tomorrow!!!

Note the crappy small vanes on the flowkooler pump. They apparently turn down a cast iron impeller that is similar to the one on the kragan pump (the flowkooler pump has the outermost part of the vanes milled off) and weld their metal shield on it. There is about 3/4 inch of vanes on the flowkooler and almost 2 inches of vanes on the kragan!

[Old Goat 67]

Thanks Mike,
Having never held one of those in my hands, I now feel I have.
Charles

[mikeb]

Well, they say that a picture tells 1000 words We changed the pump and also changed the temp sending unit. On a 90 degree, hot humid day in texas with the car in the garage, with limited airflow, and after 10 minutes at idle and revving the engine, this is as hot as we could get it to read. I may have to change out the 180 thermostat for the 192 that the parts store guy told me was stock LOL......

Thanks to all of you that figured out the way for the rest of us!

[Old Goat 67]

Ain't that sumtin.
Now you gotta worry about it running too cold.

[gtoformula]

mikeb,
Where did you find a Kragen in the DFW area. I might need one of those nice water pumps.

[mikeb]

Originally Posted by gtoformula

mikeb,
Where did you find a Kragen in the DFW area. I might need one of those nice water pumps.

I'm working in san diego, and I found it out here. California is crazy with the stores that they have out here - vons = safeway, ralphs = kroger, and kragan = orielly.

[Z Code 400]

Stock water pump, stamped impeller, .060" between impeller and divider plate, Robertshaw 160° thermostat, 3 row copper-brass radiator. The first photo shown taken at 75mph on a +100°F day. With 7 blade Lincoln Flex Fan, this is the highest the temperature guage will ever go....period, under any ambient temperature and the readings were verified with mechanical guages and infra-red heat gun...Robert

[george kujanski]

Robert, your speedo seems to be stuck at 130.........

George

[Z Code 400]

Originally Posted by george kujanski

Robert, your speedo seems to be stuck at 130.........

George

The two attached photos were taken during a pursuit driving course at the local police academy where I played the role of the 'bad guy' in my 1975 Formula. My passenger shot the two photos...Robert

[aronhk_md]

George.....great thread. Ever think of becoming a detective? LOL. I do have a question or two though. Two or three times in this thread I have seen people mention adjusting the impeller on the shaft to get the clearances correct. Not saying hammering the plate might not be necessary, but dont you think that maybe before doing that one should try to get the impeller moved on the shaft?

Reason I ask is the huge variation in gap I have seen reading through this. Seems to me the impeller is the most precise adjustment one could make.......as we have heard some here report whacking on the plate with major force and still finding difficulty getting to the proper clearance, as well as inconsistencies in whacking the plate and the resultant deformities to the plate itself.

I know many people dont have a press, but it shouldnt be too hard for them to locate someone who does if they need to.



Also, any chance a list could be made in the first post of your thread to sum up the checkpoints that have to be made in ADDITION to your clearance idea? Some people skim this post and miss out on a lot, run out into their garages, do your trick and get very disappointed when they dont get results.............lol.........but they are always asking "any idea what I should try next?" This post by Indiangoat a couple of pages back made me wish for a laundry checklist because he had a good one going. Its not complete, but we could get you to add to it as we go and all newbies can be referred back to page 1. Things like radiator cap pressure tested, spark plug check, vacuum timing advances correctly, etc......

08-17-2007, 05:01 PM
Indiangoat
Junior Member Join Date: May 2002
Location: Northern Virginia
Posts: 18

Similar problem

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Hello:

My 455 65 goat is overheating at idle. I think when it sits around for awhile the radiator is growing filaments of corrosion that might be causing heat exchange problems. I've already checked the:

- Ignition timing ok (9 deg BTDC)
- Plug color ok (brown)
- Jet and rod combo ok (standard for 428 Pontiac)
- Idle screws set ok (2.75 turns out)
- Fan clutch play ok (when cool the fan will spin less than one revolution when slung by hand)
- Fan shroud fit ok (only 1/4 inch gap on sides)
- Fan pulley function ok (tight),
- Fan pitch and air flow through radiator ok (piece of paper will stick to front grill when car runs hot)
- Water pump ok (new high flow aluminum water pump installed with high flow 160 deg t-stat)
- Coolant flow (not sure if its good. visual observations indicate that fluid passes by filler neck hole at about 1 to 2 inches per second. If I had a laser temp gauge I would use it to look for temp variations in radiator and block)
- Radiator hose spring to prevent hose collapse from suction is no problem (little rust on spring)
- Radiator fluid level (full but has some particulate material floating around)
- Temp gauge operation ok (Temp reading (230 deg) not confirmed but rad hoses get way too tight and engine gives off too much heat after running 15-20 minutes with outside air temp in the 90s)
- Compression test for head gasket failure ok (no turbulent bubbles or oil floating in radiator),
- No vacuum leaks on carb mounting gasket (67 carb - new metal/fiber base plate gasket)
- Only slight looseness in carburetor throttle shaft (slight air leak at shaft confirmed with carb cleaner test).

I think I need to replace my 15.5 inch 1965 Pontiac radiator. It's 11 years old and I can see some corrosion building inside which i think may have been caused by chlorinated tap water. Also, after working on the water pump and water neck over the years, I think its possible that little strands of gasket maker-sealer may have found their way inside the radiator tubes. I have decided to try a new Rodney Red aluminum radiator. Once I flush out the engine and install the new radiator, I'll dissect the old one and see what's inside.

Should I proceed?

Cruise and stay cool.

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Last edited by Indiangoat; 08-17-2007 at 06:04 PM.


On a final note, I wanted to just reiterate that these cars ran fine from the factory and did not overheat. Things I can think of that have changed even if your car is bone stock and was sitting in an airless vacuum with 10,000 original miles is the fuel and oil. Fuel is very different than it was, and although oil is supposedly better nowadays and I wont argue that fact, the composition is certainly different.......ie; zinc content, etc. But I tend to think the fuel might make the most difference. Could the 10% ethanol make these engines run leaner on the same jet settings they came from the factory with?

And hey...............thanks again for the thread!

[aronhk_md]

Sorry PMD.....I meant to include you as its your thread too