Pontiac Street Performance
Home | Profile | Register | Active Topics | Members | Search | FAQ
Username:
Password:
Save Password

 All Forums
 Pontiac Performance
 Cooling Tech
 461 temp creeping up
 New Topic  Reply to Topic
 Printer Friendly
Author Previous Topic Topic Next Topic  

poncho1
Buffalo

41 Posts

Posted - 04 Sep 2010 :  09:27:20 AM  Show Profile  Reply with Quote
Ok i have a 70 GTO with a stoked 400 4 core rad stock clutch fan all the basic stuff on the engine. The engine used to run 190 all the time and never waiver more then 5 deg up or down. This engine has run like this for 4 years but now it will run 190 when fist started and driven for 5 miles or 100 miles but as soon as it is shut off and cools down a bit and restarted it will shoot up to 230 while driving, pull over let it idle for a few minutes it will go back to 190, drive it some more and back up to 230. I flushed the coolant out had the rad checked out along with the cap and put in a new 160 tstat this had no effect what so ever on the problem. I dont drive this car much but am affraid to drive it now as I dont want to damage anything. The engine has not overheated but it does seem like it is getting ready to. Anyone ever have this problem before?

Phil
The Great White Buffalo

USA
7222 Posts

Posted - 04 Sep 2010 :  11:51:04 AM  Show Profile  Reply with Quote
Your description sounds like the rad and fan are doing their job because you are ok at idle. What cam/compression and how is the timing set up? What clutch on the fan and is it in proper working order? Shroud installed with fan @50% in and out?
What approx rpms are you cruising at when the temp is up?

Is the temp sender in the same location as the last engine?

Bowties are for Pee-wee Herman. "Chevy": even the name sounds cheap, but not as cheap as your Pontiac will be with an LS transplant.

Edited by - Phil on 04 Sep 2010 11:52:25 AM
Go to Top of Page

cortcomp
Coyote

USA
5338 Posts

Posted - 04 Sep 2010 :  12:19:39 PM  Show Profile  Visit cortcomp's Homepage  Reply with Quote
If you haven't changed the setup at all, i'd wonder what could change on its own and start there.

I'd start to wonder if the water pump is going? Cavitating and not pumping efficiently when at speed? Water pump divider plate rusted through (never seen this but heard it happens, i put stainless in mine)

Also, +1 on the fan clutch. Hayden makes an HD one for Pontiacs. A little stiffer than stock (it doesn't let the fan coast as much) but mines new and might break in a bit. Wiggle the fan and see if there's any play forward and back, that could indicate clutch bearing or water pump bearing issues.

Double check timing and check your spark plugs and see if they look too dark or too light. Maybe something has gotten fouled up in the fuel mixture and you're running lean or you have a vacuum leak or your timing is too advanced or retarded or a combination of things that finally started to overcome your cooling system?

If you start changing things just because, i found that the crank pulley was bigger and the water pump pulley smaller on my 75 455 with A/C than with my 69 428 without. I used that bracket and pulley setup on the 428 because the slight differences should give a little more water pump RPMS at idle. You seem to be ok at idle, thought i'd mention it though.

If you do find water pump issues, i recommend the flow kooler aluminum high flow pump. With a 160 stat (and a decent aluminum radiator) my 428 sat at 165 degrees all day (measured at the water crossover) even when i had the 10:1 compression heads on. (down to about 9.2:1 now). I did have to "massage" the divider plate as jim hand describes, i had 1/4" of clearance before i did that.
Go to Top of Page

cortcomp
Coyote

USA
5338 Posts

Posted - 04 Sep 2010 :  12:20:45 PM  Show Profile  Visit cortcomp's Homepage  Reply with Quote
Also, forgot to check the obvious: Is the car on fire? My dad's 69 gto had rubber fuel lines on the tri power which leaked and caused an engine bay fire. Step one: Check if car is on fire. They run hotter on fire. Step 2, go through the basics above and see what you find.
Go to Top of Page

poncho1
Buffalo

41 Posts

Posted - 04 Sep 2010 :  1:04:19 PM  Show Profile  Reply with Quote
The specifics on the engine are 461, 9.5 CR, 4 speed, summit 2208 cam with 1.65 rockers, mildly ported #12 heads, hooker headers, 1970 iron intake and the carb is a 1970 quadrajet. Timing was set to 13degrees initialy and the engine seems to like it there, with no pinging and no hard start problems evident. Fan is installed in the shroud 50% as it should be. I will check the things mentioned here and let you know what I find out.
thanks for the help
Go to Top of Page

cortcomp
Coyote

USA
5338 Posts

Posted - 04 Sep 2010 :  3:29:53 PM  Show Profile  Visit cortcomp's Homepage  Reply with Quote
That setup seems like it shouldn't be running too hot...something small has changed on you. I'd put my money on water pump wear, but i've been wrong before. A lot. Keep us updated!
Go to Top of Page

Phil
The Great White Buffalo

USA
7222 Posts

Posted - 04 Sep 2010 :  3:49:44 PM  Show Profile  Reply with Quote
One big change is the extra cubes which increases the load on the cooling system, as well as the general combo.

Bowties are for Pee-wee Herman. "Chevy": even the name sounds cheap, but not as cheap as your Pontiac will be with an LS transplant.
Go to Top of Page

rad400
War Paint

USA
1251 Posts

Posted - 04 Sep 2010 :  6:06:32 PM  Show Profile  Reply with Quote
Get a 5.5" wp pulley and clearance the divider plate behind the wp. To .100"

Conrad
79 Trans Am 400 auto Crower 60210 Torker II Holley 750 vac sec. #12 heads,3500 stall.
Go to Top of Page

bnorris_74
Crazy Horse

USA
1442 Posts

Posted - 04 Sep 2010 :  7:48:32 PM  Show Profile  Reply with Quote
I'll throw out the idea to check your hoses to see if one of them is collapsing. On rare occasions, the inner part of the hose will pull away from the plies of the outer carcass and suck shut from inside.
Go to Top of Page

poncho1
Buffalo

41 Posts

Posted - 05 Sep 2010 :  10:23:17 AM  Show Profile  Reply with Quote
ok so yesterday I checked a bunch of things and richened up the carb just a bit hen took it for a spin. The thing is running very good and the temp stayed right at 190. I brought it home let ie sit for about an hour and then took it to a friends house it still stayed at 190. All of this was during the day with the lights off but on the way home I noticed that the light on the temp gauge is a lot brighter then the oil gauge that it is next to. This is an aftermarket gauge assembly so I am questioning its accuracy. The gauge was reading as high as 260 at some points so I turned off the gauge lights and sure enough the temp strted to go back down. I think ill need to replace the gauge and see what happens but I think for now Ill just disconenct the power to the gauge lights and see if that makes it read correctly. I did not realize it but I always had this problem at night. Question is could the bulb cause the gauge to read incorrect.
Go to Top of Page

Chicagogoat
Cochise

USA
823 Posts

Posted - 05 Sep 2010 :  9:56:24 PM  Show Profile  Visit Chicagogoat's Homepage  Reply with Quote
Is the temp. sensor a mechanical type (a sensor with a capillary tube that feeds directly into the gauge)? Or an electric sending unit type sensor? Mechanical type: Look for kinks or damage to the cap. tube. Elec. sensor type: check and trace wiring to sensor. This should quickly rule out gauge malfunction. If your still unsure about the gauge then manually check the temp with preferably an infared temp gun or even a thermometer shoved into the rad. core. I would also recomend , as previously stated, rule out your water pump and fan clutch. I've had intermittent overheating before only to find a worn non-thermal fan clutch which was swapped for a HD thermal clutch.

Pure Pontiac: learn it, live it, love it!
Go to Top of Page

overruled
Tribal Scout

USA
1 Posts

Posted - 28 Oct 2012 :  4:46:29 PM  Show Profile  Visit overruled's Homepage  Reply with Quote
I think it is time to find a good gauge mechanical and hook it up even if temporary. Just because when you turn off the lights and see a temp you like does not make it correct. find the truth then and only then will you know you are good. I have chased these issues may times and usually found timing octane return radiator hose collapsing under high rpm, fan clutch and yes crappy rebuilt water pumps. Once a blown head gasket. Start with know if you truly have a problem then look at the facts. too lean can be intake/vacuum or carb tuning causing a "too hot" motor. Start easy and no cost diag first and then take it up a step. It apparently came on suddenly so look at what could be sudden. vacuum leak... low octane fuel.. faulty thermostat or water pump. loose belt weakening hoses (collapsing lower hose should have spring inside) Good luck

DJB
Go to Top of Page

Blued and Painted
Chief PONTIAC

USA
3409 Posts

Posted - 29 Oct 2012 :  10:09:06 AM  Show Profile  Reply with Quote
Well thought out post overruled and may be helpfull for someone but for poncho 1 it's 2 years to late.


Bull Nose Formula/ 461/ Q-Jet/
TH400/ 3.08 8.5 / R44TS.

Edited by - Blued and Painted on 29 Oct 2012 10:35:47 AM
Go to Top of Page
  Previous Topic Topic Next Topic  
 New Topic  Reply to Topic
 Printer Friendly
Jump To:
Pontiac Street Performance © 2006-2017 Go To Top Of Page
This page was generated in 0.14 seconds. This Site Sponsored By:
Powered By: Snitz Forums 2000 Version 3.4.05