Pulling what little hair i have left out (please help)
 

I have a 64 gto with a 68 400 in it. New build with a 30 over on the block. I added a Big aluminum radiator big electric puller fan. I have worked the divider plates on the water pump(cast impeller) to very tight tolerences along with directing the rear head outlet (to heater core) back to the passenger side water Crossover and my temp sender is in the driver side. I can't get this car to cool at all. I have flow thru the radiator and I have verified temps with a laser thermometer. The radiator is cool (130-160) and the motor keeps climbing till I hit about 250 and I shut it down. Please tell me there is something I am missing. Also the timing is perfect. Just installed a Holley 750 to make sure I had adequate fuel.

How many miles are on the car?

heat
 

Garage asked an excellent question. When my motor was freshened with new
bearings, rings and cam and lifters she ran a little to the warm side if allowed to
idle in garage after the breakin was done. As soon aas driven on rode she was cool.

After 100 miles she ran cool even at idle in traffic. Also keep idle up to atleast 600
in gear, keeps lots of oil splash on cam and lifter and helps with keeping waterpump spinning at a good rate.

Also is the water pump pulley smaller than crank? Ask me how i know!!!

Gerry C

Are you sure the electric fan pulls? Many aftermarket fans have the option to choose pull or push..... and do you have a fan shroud? My experience is that a good working mechanical fan with a thermoclutch works better and pulls more air than an electric one.

It is a fresh build with around 70 miles on it. Fan is pulling air correctly and is in a custom built aluminum shroud to maximize air pull over the entire core. It doesn't cool idling or running down the road. Although the radiator temp is good around 130-160 but the engine will be at 210 or higher.

Air in the system

Thermostat stuck shut

Exhaust gas in the coolant

That is where I would look.

I have two 1/8 holes on the sides of the t_stat to eliminate air and have the system topped off with an overflow plummed in to help keep it topped off.

Also its a manual 4 speed and the idle is set at 750-800.

Exhaust gas?

If your radiator is that cool then it must be a flow problem from the engine to the radiator. try taking out the thermostat and see what happens. Easy test and I wouldn't recommend not running one.

jray1,

Do you have a radiator cap that builds 15-16psi into the system?

Karl

:usflag:

Tried that. Same result.

Yes New cap

Exhaust gas in the coolant means that there could be a cracked head. The hot exhaust gas superheats the coolant. There are kits that you can buy at auto parts stores.

Do you have a coolant system pressure tester?

With it being a fresh build and having the heads checked with a complete valve job and refresh I wouldn't think there would be a crack in them. Something I just read on another Site said that there were 2 waterpump gaskets used. One on the timing cover housing followed by the divider plates then the other gasket followed by the waterpump. On mine the divider plates set inside the timing cover housing against a lip and only one gasket was needed. Now I am wondering if the divider plates are wrong or worn down. Any ideas if that might be culprit?

You say radiator keeps at ~160 and engine rises to 250. How and where are you doing these measurements?

There should be two gaskets. there should be one on the timing cover, then the plate with the same holes as the outside of the cover, then the other gasket and water pump. Also dont forget about the water pump sleeves that go into the timing cover.

Infrared shooting at the water crossover where the temp sending unit is and the radiator inlet and outlet areas as well as several areas of the hoses. Done withe the car running.

Pre 69 doesn't use sleeves unless there is something different about a 68 gto 400.

I'm not sure measuring this with an infrared unit is reliable. Get a real temp gage and sending unit to ensure you're not chasing ghosts. Or at least compare your measurements on a other engine that runs OK.

New autometer temp gauge and sending unit is exactly what the infrared is reading at the sending unit. Makes me think its right. After I pass the 230 mark there is enough pressure to push out to the overflow.

Ok. Check the pump, gasket and dividerplate as suggested earlier. I would also check for exhaust fumes in the coolant. A good repairshop should have the equipment to check the exhaust gases, in this case you should use it on the coolant (not directly in the liquid though). Do you have the springs in the radiator-hoses to prevent them from collapsing?

Still need to know a 100% about the divider plate as to whether or not the 68 requires 2 gaskets or one. If it is 2 I have the wrong dividers as the ones I have fit inside The timing cover And not in between 2 gaskets. Just trying to double check every part and possible problem.

You have water that is 230 degrees in the block and water that is 130 in the radiator, you have a flow problem. Either there is a physical obstruction in the block preventing the water from leaving or the pump is inadequate to move the water out of the radiator into the block.

Those are my exact thoughts. I would pull the thermostat and check the flow with a garden hose. ( with the car off)

That's what I have been kind of thinking but I see it circulating thru the radiator. Just may not be enough. I don't know what to do if it is slow flow as I stated before its a fresh build and the block was tanked and cleaned at the machine shop. I will try to check the flow more closely and try to figure out if it is enough.

Just by looking at the radiator through the cap opening is not going to be enough to determine flow. I have been trying to think of a way to test flow but cannot think of one. Go back and look at post #17, the pump, the impeller, and the divider plate all have to be correct in order for the pump to pull enough vacuum to ensure correct flow.

Will be pulling the pump again tomorrow to recheck all of it. Just wish I could get a 100% confirmation on the divider plates. The ones I have with my 8 bolt water fit inside the timing cover housing and only 1 gasket is used. If this is wrong it could be part of my problem.

When you pull the pump please take some pictures. I would like to see what the pump looks like.

I would also like to see what the fan looks like. I have a pretty big fan and I would like to see yours and the shroud.

I also found this the other day. Looks cool and is a great diagnosis tool. I would get the Chevy one as the Pontiac one looks too big for no good reason..

http://www.coolviewthermostat.com/

Dave

I will take some pics to post tomorrow that may be a big help.

After a long talk with Jim Butler from Butler Performance yesterday I decided to wait before pulling everything a part again and recheck the basics. Great bunch to deal with if you haven't already. After our discussion we determined my timing wasn't set correctly (needed set with vacuum hooked up). Done this morning only to discover that at 2500-3000 rpms I am getting about 45 degrees of total timing (not good). Got to get that fixed before going any further.

Also there was mention of a possible issue if I used felpro head gaskets (which I did) concerning the water jacket holes in the gasket. The water jacket is a 3/8 and the gasket is 3/4 which gets it real close to the compression ring in some cases. I hope that's not my problem.

I blew both head gaskets when I put mine together about 10 months ago because of the problem with the felpro head gaskets. All it did was a small hic-up & blew the head gaskets. I to talked to Jim about this problem. The best thing to do is replace the head gaskets with the ones Jim says to & be done with it. His gaskets don't have that problem . It sounds like you blew your head gasket(s) as I did. Your problem sounds just like what i went through until I to talked to Jim about the problem. Change them & be done with it. You'll be much happier in the long run by doing it. Then your problem will be gone & you can drive the car without worry.

I really, really hope that's not what it is but if so Jim will be the first person I talk to and the gaskets will be ordered. I hope the timing is the problem (fingers crossed).

Ok I unhooked the vacuum on the distributor and reset the timing to 16 initial. Reset the carb mix and idle Drove it down the road a few miles and it ran great and never got over 190. Even though it was in the lower 60's this morning I think I may have got most of the problem under control. Big thanks to everyone for your help and also to Jim Butler for giving me a call back.

And to calm your fears about the water pump, on the 8 bolt design like yours (68 model), there is only one gasket. The divider plate indeed sits inside of the timing cover, and doesn't require a second gasket OR the sleeves that the later (69 and up) 11 bolt designs do with 2 gaskets.

Glad to hear you're getting it fixed!

:)

Great thanks.

Attachment 297908 Maybe I will finally get to see this blue outside instead of just in the garage.

I don't think your going to be any happier after you rset your timming. If it were an issue of timming all the coolant in your system would be hot at the same time. I went through the same things hoping it wasn't that but in the long run it was the head gaskets. Just look at it this way the longer you wait the longer you don't get to drive the car. Just break down & break in down tear it down & replace the head gaskets now to save a little of that OH so prrious time & replace them. If it were timming the coolant would heat up as it was circulating & it would all be hot not just in the engine until it gets so hot it bloes the raditor cap seal into the overflow. I know you want the best news, & I have to ask have you taken the t-stat out & run it without it in the engine & watched the coolant to see if it is circulating & if so was there bubbles in the coolant while it was going around??? If you have bubbles you have a blown head gasket(s).

Well after pulling the vacuum and resetting the timing then taking on a 6-7 mile spirited drive it never got above 190 . I have pulled the t-stat prior to this and the water is flowing thru without bubbles so I am still hoping its not the new head gasket and was just way to much timing.

I have the same exact symptoms going on. I also used an IR themometer with the same results. I have an aluminum radiator with electric fans, checked the water pump clearances, etc.
I bought a new water pump (PWP381) from cardone that's supposed to have an improved impeller. I was gonna install it tonight but, looks like I better check my timing instead. What's funny about mine is it ran cool for the first 75 miles or so then overheated. It now will overheat while idling or driving only a mile or so. The distributor is tight so I know it didn't move. I will check it this evening.

The problem with mines so far seemed to be the vacuum advance. The initial timing was where it needed to be but the vacuum pulled in way to much timing way to fast. I should max out at 36 degrees of timing but I was hitting 45-46 possibly more at higher rpms. Without vacuum it will max at 36 and the mechanical curve seems great for this motor so far. Also I should mention this is an HEI distributor not the points style.

I have an HEI also. Even at idle the vac advance is pulling too much? My car will overheat just idling. I thought I set my initial timing at 12 degrees but, never check what the advance was doing. I wonder if the vac advances we have are faulty? Going out to look at mine now.

I truely think the hei With the vacuum hooked up just advances way to fast for the motor. Try unhooking the vacuum lines and plugging the vacuum ports then set your timing around 14-16 degrees advanced. Rev it to around 2500-3000 rpms and you should be at max advance. Shouldn't go past 36 degrees advance.

Well.... I thought I had the vac advance problem. I had about 8 degrees initial and when plugging vac advance in it looked like it went to over 40 degrees advanced at idle! I have an adjustable vac advance canister so I backed it all the way out. I adjusted my initial to about 12-13 and adjusted the vac advance to add another 12 or so. After that I adjusted my air/fuel and idle on my carb. Done all this in 5-10 minutes while keeping an eye on my temp. It still crept up to 230 in that short period of time :(. I borrowed a hydrocarbon tested from a friend tonight to test my coolant. Afraid I have the head gasket issue. Makes sense because my setup ran for hours three or 4 times but, since I drove it for an hour and it got hot it overheats within 5-10 minutes idling. Even faster while driving...

Sorry to hear , I hope though now you can get it fixed & have no more problems once it gets fixed. None of us ever like to hear of any of us having any problems with our toys but at least now it has a possible end. If there is any thing we can help with in the future drop a line & some one here will be glad to help.

Sorry to hear that, after getting some more time to check mine yesterday I am not totally out of the woods either. Mine is running way cooler now it takes a long time for the temp to get up but it wants to go to 200-205 and stay there. Since I have a 160 thermostat I am wondering now if there is a flow issue as well.

I suspect you have the same deal as a bunch of guys, there are a few different issues contributing to your higher than desired temps. Notice I said higher than desired and not over heating. Some guys find a few degrees here and there by going through everything that can cause higher temps. They find dragging brakes, timing and fuel mixture issues, a few thousandths off on water pump plate clearance, radiator is dirty, plugged or wrong model for the application, bad fan clutch, wrong clutch or fan, fan incorrect distance from radiator, no shroud, wrong or incorrect fitting of shroud, or wrong amount of fan in and out of shroud................... I'm tired of typing!

Karl

:usflag:

jray,

Splain this to me again? By "crossover" do you mean the timing cover return fitting? The stock way my '72 is set up is as follows; the passenger side head has a fitting at the rear that feeds the heater core, the heater core then sends the water to the return fitting on the timing cover. The driver side head has no external water flow. To bypass the heater core I run a heater hose from the rear of the passenger side head to the timing cover return.

Karl

:usflag:

Right now I have the hose out the back passenger head that goes to the heater core t'd So it goes from the back of the head to the passenger side of the intake. With a vintage air system there is an electric valve that doesn't open to let the hot water thru to the heater core until u turn it on heat. I was afraid the lack of flow here could have been part of my problem.