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#1
03-11-2020, 11:35 AM
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water pump must have cast impeller and gap at separator ..035 to 050 not .250
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 BOB SLUSSER 937-286-4343 |
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#2
03-08-2020, 04:36 AM
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Check that vacuum advance is connected...& working. Engine needs extra timing at cruise to run cool.
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#3
03-08-2020, 11:44 AM
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Is it actually overheating? Like as in boiling over? How long before it has to be shut down? What kind of fan shroud combination does it have?
I know it's a fresh rebuild but you should get it tested for a head gasket leak as well as the other suggestions.
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--------------------------- Fool Around, Get Hurt, Don't come Crying to me. |
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#4
03-08-2020, 11:52 AM
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As for the shrouding...Its not here yet, but he said they have tried different shrouds, fans, etc...I'll know more when it gets here. |
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#5
03-08-2020, 12:17 PM
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Quote:
__________________
--------------------------- Fool Around, Get Hurt, Don't come Crying to me. |
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#6
03-08-2020, 12:56 PM
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This is the problem with most discussions...If he continued to drive, it'll boil over and tear it up, and we all know that...So, rather than try to talk about 220 is not "over heating", lets stick to what I posted... Now, while I know you'll think i'm being an ass for saying that, think through what I have said from the start of this thread...I will do the head gasket checks along the way, but based on what he has told me, it doesnt seem to be a head gasket...He can make hard 1/8th mile hits, with no issue...I would expect a head gasket to show signs under full throttle pulls like that...But, it will get checked out too... Again, it only stops climbing due to the fact that he pulls off the highway... |
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#7
03-08-2020, 03:28 PM
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What your symptoms mean to me is that there is not enough air flow at higher speeds seeing it cools down at lower speeds where I am assuming a good fan takes over and draws enough air through. Couple of quick checks that may seem simple - is the anti-freeze the correct mix? 50/50? Is the radiator cap good, sealing, and 15 PSI? Keep in mind that the expansion tank does not get filled to the top on the older cars. If you do, they will push coolant out until it "normalizes." The factory manual, as I recall, says it will be 2-3" from the top. The cooling tubes should be covered. Have you pulled the cap when cold and observed the coolant flow while looking down into the expansion tank? You should be able to see the coolant sitting steady, not flowing, when cold, and then watch is slowly begin to flow as the T-stat opens, and then flow well once it reaches full temp based on the T-stat temp. A slipping belt. Yep, had that happen. The belt appears to set in the pulley correctly, but in fact is set too deep and is riding on the center of the pulley instead of the pulley grooves/sides. So at higher RPM's, with more grip needed to rotate the fan, the belt is actually slipping around the pulley center. You won't hear any squealing or signs of a problem because it is rotating, just not grabbing. The replacement belts are often metric and not correct for our old car applications. I found that the Dayco top-cog belts worked best for me and sat in the pulley groove where it should and ot down low in the pulley groove riding on its center hub slipping away. That said, first thing would be to have the radiator boiled out and checked. I did not see this mentioned by you. If by chance you have an aluminum radiator, it could be possible that the tubes are too small or too tightly placed together to provide sufficient cooling/air flow. Either way, I would still have it boiled out and tested as it is possible that there is junk in it even if new. Next, is the thermostat. I have had the experience of brand new T-stats, made overseas crap, go bad shortly after installation. I don't think they use the best quality metals and after a couple cycles of open/close, they fatigue and stop working. I use a 160 degree T-stat and I am going to get flak that it is too cold, the engine doesn't get hot enough to rid the oil/engine of moisture, you heater won't get too hot in winter, and anything else that critics can come up with. So get a 160 T-stat if you are already not using one. But, what you want to do is drill two (2) 1/8" holes in the brass ring between the center and outer rim - where you won't be causing any sealing issues. Why? This allows trapped air out which can create a bubble in the cooling system and cause it to run hot/overheat. It can also be in your favor should the T-stat close down if it fails and allows the cooling system pressure through, however small, and won't puke explosively back out through the engine, bottom hose, and out the cap. My experience has also been that the overheating, which it is going to do if the T-stat collapses, will rise steady, but slower and give you just a little more time/edge to get to a safe place. You can also purchase a T-stat having the pressure relief valves built in. Here is an example of the Milodon high-flow 180 degree T-stat with the brass relief valves built in. https://www.jegs.com/i/Milodon/697/1...SABEgI77vD_BwE Here is the 160 T-stat, but does not show the brass valves, but assume they are there, so you may want to inquire if you go that route: https://www.jegs.com/i/Milodon/697/16400/10002/-1 Other suggestions mentioned are good things to look into. Bottom hose collapsing at higher speeds as the water pump turns faster and can cause enough suction on the lower hose to collapse. If you do not have a hose with the spring/expander inside to keep the form of the hose round, you can either purchase a hose with the spring/expander or jut buy the spring and install. It could be a timing issue, ie too much advance, both mechanical or vacuum. Check the initial at the balancer, then determine the distributor's advance curve and what the RPM is that full advance (balancer + distributor weights) come in at (with the vacuum advance disconnected). The total may be coming in too soon for that engine combo. The vacuum advance should be used for a street car and can provide better gas mileage along with engine cooling at part/no throttle driving. But, if the mechanical is way too high, the vacuum gets added to this and can aggravate the problem rather than help. If the engine is running too lean it will heat up. You may have a mixture that works at lower speeds, but once the RPM's increase, not enough fuel is getting to the engine causing it too lean out - which means running hot. The carb could be clogged somewhere or jetting too lean. Other things to check could be the fuel pump not delivering enough fuel at higher RPM's, the "sock" at the end of the pick-up tube in the gas tank has collapsed or is plugged, wrong gas cap and the tank is not venting creating a vacuum inside it and not allowing enough fuel to flow through the lines, cracked/split rubber lines letting air in rather than the needed fuel at higher RPM's. Camshaft not dialed in correctly. The intake and exhaust valves not closing at the right time, ie jumped timing, cam installed using wrong cam key position, cam gears off a tooth or two when installed. Sloppy/worn timing chain/gears. If factory chain/gears, they used a nylon coated cam gear and it wears out around 60K miles and should be changed. So there could be a number of things to check. Just have to check step at a time and not to many changes at any one time. Sometimes to know what it is, you have to rule out what it is not. |
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#8
03-08-2020, 04:25 PM
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I also did not notice that he was running ok under full throttle situations. So I would now be less suspect of a head gasket leak as well. I'd now start looking at the suggestions mentioned but I'd also start asking about what kind of radiator is being used. If it's clogged or undersized, that's exactly the symptoms I would be expecting. If the radiator is clean and high capacity, although not out of the question, it's not common for a thermostat, bad fan shroud, missing spring in hose or even timing to run the temperature to a boiling point. . .
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--------------------------- Fool Around, Get Hurt, Don't come Crying to me. |
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#9
03-11-2020, 08:08 PM
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Fans are running correctly...
I jetted the carb up...No help Advanced timing...No help... Swapped the T-stat and will test in the morning... If that doesnt help, i'm going to pulled the electric fans, and install a factory shroud and 7 blade fan... I did notice that the car has a bunch of gear, and it turning 3500RPM to go 65mph... |
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#10
03-11-2020, 08:45 PM
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So one condition I had with a similar setup, where a car with gear at highway speeds, say 3500-4500 RPM, at part throttle/low load, would pull the vacuum advance enough to where it would start running hotter. Try running it with no vacuum advance and see if it still does it.
That won't help at lower speed driving & idle obviously, but the only way to get around that is to go to a electronic controller advance, such as the MSD programmable 6-AL with a MAP sensor or EFI ECU. .
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. 1970 GTO Judge Tribute Pro-Tour Project 535 IA2 http://forums.maxperformanceinc.com/...d.php?t=760624 1971 Trans Am 463, 315cfm E-head Sniper XFlow EFI, TKO600 extreme, 9", GW suspension, Baer brakes, pro tour car https://forums.maxperformanceinc.com...ght=procharger Theme Song: http://www.youtube.com/watch?v=7zKAS...ature=youtu.be |
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#11
03-12-2020, 10:02 AM
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So how much timing are you seeing at 3500 RPM's? With centrifugal and with vacuum advance. Clay |
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#12
03-08-2020, 04:18 PM
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Have you checked how efficient the radiator is at idle?Get a lazer heat gun and see if you have at least a 40 degree drop from where the water enters and leaves the radiator.Tom
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#13
03-08-2020, 04:34 PM
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Ok, car made it here today...
It has a wide 4 core brass/copper radiator, with a pair of electric fans that are made to a shroud that completely covers the core... At first look, it doesnt look like it has the plate between the pump and timing cover...It is an aftermarket cover, so i'll have to figure that out first... Its a really nice 68 convertible, that the guy has spared no expense, but it seems he had it at a few shops that didnt care about quality... I'll let you guy know how it goes, and I do appreciate all of the opinions... |
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#14
03-11-2020, 11:56 AM
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GM, when first building shroud technology put holes in the shroud and had 20+ Vacuum gauges all over them to test the airflow Pull at ALL parts of the radiator. Its easy to have a cooling "fail" even when the radiator is covered by a "metal shroud" You would be surprised to see how well a stock fan shroud and a clutch fan would work for POWER and Cooling. Highway driving burns MORE calories= More heat, and guess what?, the air flow in that set up does NOT increase... = heat build up.. Good luck. |
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#15
03-08-2020, 09:04 PM
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It has a wide 4 core brass/copper radiator, with a pair of electric fans that are made to a shroud that completely covers the core...
At first look, it doesnt look like it has the plate between the pump and timing cover...It is an aftermarket cover, so i'll have to figure that out first... I would think the first statement is the issue. The fan asm's are probably restricting air flow at highway speeds. I would also want the A/C cover's as B-man referenced. just my wag. If it didn't have the divider plates I would think it would overheat in the staging lanes...
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72 Luxury Lemans nicely optioned  Best so far 12.40 Milan Dragway 2025 I am the Thread Killer! |
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#16
03-08-2020, 09:11 PM
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1964 Tempest Coupe LS3/4L70E/3.42 1964 Le Mans Convertible 421 HO/TH350/3.08 2002 WS6 Convertible LS1/4L60E/3.23 1966 VW Type 2 Single Cab Pickup 140hp 2276 1956 VW Type 2 Panel Van 36hp 1200 1957 VW Type 1 Beetle 180hp 2276 |
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#17
03-11-2020, 04:48 PM
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The water pump separator plate will normally cause overheating in traffic driving at lower speeds. Two things come to my mind that haven't been mentioned, the first and I'm sure it has been checked by one of the shops, is make sure the fans are wired correctly and are directing air across the radiator instead of pusing it forward. The next thing that hasn't been mentioned is, if the car has an automatic transmission, the trans could be overheating causing excessive heat in the engine cooling system from trans. cooler in radiator.
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#18
03-12-2020, 11:58 AM
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I fought with cooling on my Firebird and tried many different fans, shrouds, radiators, A/C / 400 baffles on the top & bottom, etc... What I ended up with was a Cold Case radiator & Spal extreme duty fans, but the biggest difference was when I removed the thermostat so the water could FLOW. Even the "high flow" thermostat caused too much restriction. Faster flow = cooler water. After that, temps stayed at, or below, 195*-200*. The only time the temps creeped over 200* was extended highway driving around 3500 rpm.
I'd be curious what the oil temps are. With the large mains in a 455, mine would climb at the higher rpm driving and would push the water temps up with it. There's a lot of good suggestions above, but I would remove the t-stat & see if that helps. Faster flow = cooler temps. My checklist (From Least $ to More $$$: Timing Spring in lower hose Remove T-stat Diver plate clearance Seal around radiator - Black foam water pipe insulation works good & is easy to seal the gap. Good/big enough radiator Proper/enough fan(s) Upper & lower baffles
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No! Do not try! Do! Or do not. There is no try. - Yoda 1967 Firebird Restoration 2005 - 1/25/2017 
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#19
03-13-2020, 02:29 PM
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Great info, subscribing.
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"No replacement for displacement!" GTOAA--https://www.gtoaa.org/ |
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#20
03-14-2020, 03:22 AM
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Might have missed the correction, but worth stating here. The '68 timing cover was a combination of old and new. Still used the 8-bolt water pump with two plates that are not visible from the outside and the larger 4-bolt harmonic balancer. If either of the plates were missing the slow speed temps would also be through the roof.
Have a friend that went with a custom aluminum shroud/fan assembly and even with the flaps, the $1,250 assembly runs warmer on the freeway than his previous stock shroud and mechanical fan at speed.
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Mick Batson 1967 original owner Tyro Blue/black top 4-speed HO GTO with all the original parts stored safely away -- 1965 Catalina Safari Wagon. |
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