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brandyv73's 1968 Firebird

2019 June
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Frosty, yes the lower valance and the air dam are both in place. I installed the FlowKooler pump and it still overheats, although not as fast. Previously it took about 20 minutes to reach 220, now its 35-40 minutes before it reaches critical temps. I have a 165 degree thermostat in right now and I am thinking the water never stops moving as the stat never closes, my thought is its not staying in the rad long enough to transfer the heat and cycles hot water right back into already hot engine. So I'm going to try a 195 stat hoping to slow down the flow. Still open to new ideas......?

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Have you had it out on the road yet ? Or just mostly running at idle ? Was just wondering if out on the road not in stop and go traffic if it runs a steady temp around the 180 range.then goes up at significantly at stop lights and how fast it rises when stopped. Then when rolling again it drops back down.? From the factory GM didn't have the fans programmed to come on until around the 220 Mark ( of course with chevy engine)

Edited by TWO LANE BLACK TOP

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The reason they had the fans programmed at higher temps was to make the cats more efficient in stop and go traffic and at idle. Was an emission control thing. The hotter the better the old type GM pellet type cats worked. Of course I know you're not running cats.  It is really not that unusual for third and fourth gens too have a 30 degree temp swings between idling and stop and go traffic than when actually driving down the highway. With the pressurized  cooling system. Probably between 15 and 18 PSI ? You may think I'm crazy but 220 is really not overly hot in an extended idle condition. Especially if it takes 30 minutes to get there. And doesn't rise anymore than that. And it doesn't boil over. Would try it out on the open road see what it does. If the temp stays steady around 180 or so while cruising at 70 MPH then go from there. You might actually be OK.  of course you can turn your fans on at anytime with your manual control......Please let know what happens....Will be attending Charlotte Auto Fair in a couple weeks. You?

Edited by TWO LANE BLACK TOP

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I just re read the whole post and you said several entries ago that you have a 4 inch water pump pulley as opposed to the stock 6 1/2. Have you considered the possibility that you are spinning the pump too fast and you are indeed pushing the coolant through the radiator too fast. Can you put some kind of clamp on the upper hose to restrict it and slow down the coolant to see what happens. Another thought that just danced across my brain is what is your percentage of water to antifreeze. I had a desert racer friend years ago who found that his race truck cooled the best with 25% antifreeze and 75% water. 

But then as two lane observed 220 is not considered overheating. with 16 pounds pressure in the radiator your boiling point is somewhere around 260 depending on antifreeze percentage. The hot light on the 60's vintage cars that did not have a temp gauge, like my 63 Catalina, triggered around 245 to 250 and the ones with the pellet type cats had a 195 degree thermostat from the factory. Put a few gallons of water in the trunk and take it out and drive it, you may be chasing a problem that really does not exist.

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Two lane, I agree 220 is not overheating with a 16lbs cap. If it didnt rise above that I'd be ok with it but it keeps climbing and climbing, slowly. I haven't had a chance to install the 195 stat yet, maybe tonight. Charlotte would be a 11 hour round trip for me, I'd like to go but its not likely this year. Any way I had to replace the gas tank due to trash in it also installed an intank pump and aftermarket gauge sending unit. Hopefully I can take it for a spin tomorrow.

OldGuy, I made a mistake about the pulley its a 6 1/2 inch. As far as antifreeze goes it has 1.5 gallons and somewhere around 3-3.5 of water

Will update ya'll later

thx

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Was looking at the photos. Can't see where the remote oil filter is located. But I'm old and halfway blind. Was just wondering how close if at all.The oil lines going to the filter were to the exhaust manifolds or headers helping possibly making the oil temp hotter than should be??

Edited by TWO LANE BLACK TOP

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Two Lane, Good thought, the lines coming off the adapter go up and over the bell housing towards the left then under the steering shaft wrap around the inner fender well going towards the front of the car and the filter is mounted on the front of the fender well. You can see in this pic the right side exhaust is not close to the lines. But I may be on to something, it doesn't make a lot of sense but. I had to cut out my muffler in order to replace the gas tank. For S&Gs I fired it up without the muffler and it never went over 195. BackPressure to high? It didn't appear that way. New muffler and pipes. the engine was plenty responsive with that muffler. Just weird, gremlins I tell you gremlins. Anyway I'm redesigning the exhaust and using tube muffler instead of the rear mounted. TempOil.mp4

RemoteOilAdaptor.JPG

Edited by DrJones

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DrJoes, how much of the radiator is covered by your cooling fans? I see you don't have any sort of radiator shroud. I suspect that is due, in part, because of the Pontiac engine is so close to the radiator and the fans. I am wondering if the lack of a shroud is reducing the effectiveness of the cooling fans, and perhaps you need large diameter fans to cover more surface area of the radiator.

Also on my Pontiac I run the Mr Gasket wide mouth thermostat to increase coolant flow.

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How we doing today Drjones? Was looking at the photos of your radiator set up. Just had a crazy thought. Noticed that the shroud on the engine side covers the whole core of the radiator.Is it really close to the to the core without much clearance between the two? With all 4 of your fans pretty much  pushing and pulling the air just thru just the center of the radiator. With the other side covered. If there is not a lot of clearance between shroud and the radiator. For any air to circulate. Wondering  if it is creating a dead space. Not alowing air to flow freely. Thru the whole rad core Not taking advantage of all the surface area and not allowing the the ends and corners to be as efficient as they could be if the whole thing was open to the air?? After you took muffler off never never got above 195? Interesting...would think if exhaust was that restrictive would be obvious in the way the engine performed even at idle. Of course anyone that messes with mechanical stuff alot knows sometimes strange shit just happens with no rhyme or reason......

Edited by TWO LANE BLACK TOP

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Two Lane, pretty good.

The space between the shroud and rad core is somewhere around 1 inch.  Maybe not enough. The shroud came with the rad.

I should be done with the exhaust tonight. I ran out of Argon the other day and you know how bad the splatter is without any shielding gas....

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What's up Drjones.Was watching your video. No sound though.Looks likes you might be ready to take it out and have some fun with it !...Let know what happens..Also like the underhood gauges..

Edited by TWO LANE BLACK TOP

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Two Lane, Use VLC player and you should get sound

I spend alot of time under the hood hence the need for the gauges.

Took it out shortly after the video, runs like a scalded dog but still getting hot. Was running 60 and temp climbed to 230. Shut it down and sat for 30 minutes before I headed back to the house. Almost 240 by the time I get back. SCARY

Edited by DrJones

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Can barely use smart phone or my laptop.Not sure what VLC player is.. Anyway assuming has a little but of a thump to it and sounds good ?...

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Everything I see in the photos and everything you've said has covered all the bases. A couple of  times. When engine was built am assuming the block was hot tanked and there are no blockages anywhere in the block and the decks are flat and true? And all the galley plugs are for sure in place. Same thing for the cylinder heads..Other than a fresh valve job and new springs , retainers , and locks , resurfacing the heads. Was anything else done to them like opening spring pockets to accept larger diameter springs etc..? What kind of cylinder head gaskets did you use ? Were the head bolts or stud threads sealed where they screw into the block.? While assembling engine..Did you do it all yourself or did the machine shop do the the short block assembly? Just trying to get the big picture in my mind....Storming here right now. Will probably be storming down your way next few hours...

Edited by TWO LANE BLACK TOP

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41 minutes ago, TWO LANE BLACK TOP said:

Can barely use smart phone or my laptop.Not sure what VLC player is.. Anyway assuming has a little but of a thump to it and sounds good ?...

VLC is a media player for your desktop/laptop computer. Best IMO as it can play a lot of different file types. Best of all it is free, here is the official download: http://www.videolan.org/vlc/index.html

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Thanks Ringo. Will do that .Maybe get Mrs. Two lane to do for me. She is computer whiz compared too me....

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Block was hot tanked. the deck was surfaced by only a few thousandths 2 or 3.  Heads milled .010 did not enlarge spring pockets they are stock. Head gaskets are Felpro FEL-8518PT. No sealer on head bolts. Pontiac do not need thread sealant since the bolts do not break into the water jackets, did lube them.  I did all the assembly myself. I'm feeling like there must be a blockage of some sort inside the block. I'm gona get my buddy's infrared thermometer and check different ares see if I can find any hot spots.

I'm really running out of ideas. Maybe the Gen3 just won't let enough air pass to satisfy.

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Are the cooling lines for the transmission plumbed to the radiator correctly? Outflow from trans to top fitting then flow back to trans from bottom of radiator? Not 100% sure but think rear line on side of trans goes to the top of radiator. Front line on side of trans goes to bottom..Like I said Not 100% sure about that. Has been awhile.... Might be something to verify. Don't think duct design and airflow on third gen is an issue if it is all intact. When racing modifieds. Have really  similar type duct setup in front of radiator with 2 fans  as third gens do.. Have the engine side of radiator open no shroud to allow the air to flow free thru whole core with no obstruction. Running 700 Horsepower 18 degree aluminum headed solid roller 9000 RPM hardcore race engine. Temps normally run 190 to 210 under green flag conditions. At the stadium. Running between 5700 to 8800 RPMs for 200 laps. On a hot summer NC night... Rarely if ever temp gets above 225 and that's only  if run a bunch of caution laps. Also run seperate oil cooler with the dry sump oiling system holds Like 20 qts oil....Just going over some thoughts. Maybe some thing here you can use..Also have an aversion to spending money unnecessarily for things that Might not or don't work. please let know what infra red thermometer shows..

Edited by TWO LANE BLACK TOP

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JUSTA6, Indymanjoe, and I were at a local car show today. I met another '72 GTO owner with a 455. He is having similar oil consumption issues that I have (not necessarily germane to this discussion). He then said he had an overheating problem. Obviously this made be think of this thread. He said his issue was too much RTV/silicon on the water pump to intake manifold connection. It was too thick and restricted the water flow. He said his engine tuner buddy said that is rather common mistake people make who don't build Pontiacs on a regular basis and are use to overdoing RTV on Chevies and Fords.

You can see the slight amount of RTV coming out between the water pump and the intake in the photo below. He said it was extremely thick into the water flow and once he re-did it that his water temps dropped immediately. So now you have something else to consider.

IMG_3500.thumb.JPG.111db7d53cb2bef5c6faa656661dfa81.JPG

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Indyman Joe had a helpful post quite awhile ago on Pontiac water pumps.  This was not 455 related, but might be something to consider.  I made many changes to my cooling system for my 421.  Correct fan, shroud, 4 core rad, lower thermostate (180) and getting the fan as close to the rad as possible solved my prob.  Which change or combo of changes made the difference....We'll never know. 

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DrJones - any update or progess on your machine? Are you still overheating? I thought it best to check back in.

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