[462ta]

drove to car show this am, weather was cool,car ran at 180-185 for 60miles, on the way home looked at gauge after few miles and I was at 200-210, now it was warmer out but thing was if I dropped 5-10 miles an hr it would start to cool down, if I stayed around 50 or so it was 190 or so but if I went up t0 60 or so it would climb back up to 210
came home and checked timing OK advance workingOK, checked clutch fan and it was tight when hot,checked rad with temp gun and it was pretty close to guage, think gauge is \ok as it moved up and down, took similar trip week ago and all was good so don't know what changed any ideas thks--car in bio

[rustyrelic]

I had a similar problem not long ago. Turned out the thermostat was sticking. $5 part. Might be worth a shot.

[Cliff R]

TRW forged pistons? Was the block zero decked?.....Cliff

[steve25]

It could be a bunch of stuff, but many years ago when I got my first 455 I already had a well built 400 making 515 hp and the car had a oil temp gauge in it.
I latter put in a 9.4 comp stock bore 455 and soon found that with those big 3.250" mains on the crank that at around 2800 to 3200 rpm dependent on the days temp, that the motor needed a oil cooler!
This is with the water temps being the same between both motors and both using vacuum advance.
I ended up with a remote duel filter set up on the passenger side wheel well and 2 quart filters used on it, and that was enough cooling until I added a 671 roots blower on top the motor and then the oil cooler was mandatory with the temps that I saw!

[462ta]

thing is the car has been good for years something changed in last couple days. pistons are KB forged and zero decked Cliff.

[steve25]

Has the overflow been going into the tank at all?
If you had the rad cap off you may try burping the air out.
Start the motor with the rad cap off and wait for the stat to open, as it does let the rad over flow some and put the cap back on and drive it to kook for any change for the better.
Also not that you should note use tap water in the rad along with coolant, you need to keep minerals out by using denatured water!
If you used tap water I would drain the system, use a can of two part type flush and start over with the right water and amount of coolant, meaning no more than a 50/50 mix for summer and than follow the coolant flow thru your rad with your temp gun.
I would also remove the oil filter, cut it open and check for bearing material in it just to be on the safe side!

[HWYSTR455]

Originally Posted by 462ta

drove to car show this am, weather was cool,car ran at 180-185 for 60miles, on the way home looked at gauge after few miles and I was at 200-210, now it was warmer out but thing was if I dropped 5-10 miles an hr it would start to cool down, if I stayed around 50 or so it was 190 or so but if I went up t0 60 or so it would climb back up to 210
came home and checked timing OK advance workingOK, checked clutch fan and it was tight when hot,checked rad with temp gun and it was pretty close to guage, think gauge is \ok as it moved up and down, took similar trip week ago and all was good so don't know what changed any ideas thks--car in bio

The clone does the same thing, but it's always been like that. I've tried multiple thermostats, water pumps, it's got a big aluminum rad, 4600cfm fans with highway windows in the shroud, everything, still does it. Once it gets over 200, it never settles down to the stat rating until it completely cools off, runs 195+ from that point on. When it's completely cool, fire it up, around town, it's 180-190, one blast or some highway, and back to the 210 range until it cools off completely (or 190 at 50 or around town). Granted, with 342s, 70mph is like 3500 RPM, but still, ran 373s in the lemans with a TH400 for a long time, never did that. Slow down to 50 or so on the highway, right back to 190-195. Bring it back up to 60-70, 210 again. It can even creep if I keep going speed to like 230 I think is the highest I let it get. Tried different timing settings, vacuum advance changes, jetting, nothing seems to make a difference. No coolant loss, so doubt it's a head gasket. Good oil pressure and never any material in the filter.

Starting to wonder if it's a coil or something ignition related that's going on it. It's mostly used around town, so not that concerned with it at the moment, but know I need to fix it eventually.

.

[steve25]

Your Carbs primary metering rods could be getting hung and leaning things out, but not enough to make for a flat spot throttle wise at a given vacuum drop / level!
It's worth taking the Carb apart to check this and look for the remains of today's cut gas and also to blow out all the passages.

[rustyrelic]

Did you confirm that the thermostate is working?

I had a very similar problem. Ok at low speed. Ok at idle. Temp climbed at higher speed. I had had problems with overheating in the past and just assumed the problem was some deficent in the cooling system. I replaced the stamped impeller water pump with a cast iron impeller pump, replaced the lower raditor hose with a molded hose and added a internal support spring, clearanced the water pump divider and it still overheated. (Had previously replaced the fan clutch the year before trying to reduce the operating temp.)

Changed the thermostat. Problem solved. red-faced, but now I feel pretty good about the condition of the cooling system.

[HWYSTR455]

I'm on my third thermostat, but they were all out of the same batch, so guess it's possible they are all bad. Stant SuperStats. I will try a new one here shortly see if there's a difference.

.

[462ta]

replaced the thermostat yesterday, put both old and new on the stove and they both opened at same time, put new one in anyway but have not had chance to take car out-raining. rad looked good lots flow thru ,all new fluid month ago when changed all hoses.

[72LuxuryLeMansLa.]

Originally Posted by steve25

Has the overflow been going into the tank at all?
If you had the rad cap off you may try burping the air out.
Start the motor with the rad cap off and wait for the stat to open, as it does let the rad over flow some and put the cap back on and drive it to kook for any change for the better.
Also not that you should note use tap water in the rad along with coolant, you need to keep minerals out by using denatured water!
If you used tap water I would drain the system, use a can of two part type flush and start over with the right water and amount of coolant, meaning no more than a 50/50 mix for summer and than follow the coolant flow thru your rad with your temp gun.
I would also remove the oil filter, cut it open and check for bearing material in it just to be on the safe side!

Steve,

Just a FYI.....I run tap water(filtered) and sometimes rainwater. I tested my water with a simple kit I bought from http://no-rosion.com/norosionwater.htm . I use a simple charcoal filter on my kitchen tap and get my water from there or a rain barrel and the quality matches store bought R.O. Water according to the test kit. I run straight water and Hyperkuhl http://no-rosion.com/hyperkuhlcoolant.htm and have no issues with scale build up.

[Formulajones]

I'd say you have some strange issue going on if it's been fine for years and now just suddenly happens. Possibly a hose collapsing at speed? Springs inside the hoses??

With your 28" tire and only a 3.23 gear, you should only be turning in the 2,300-2,500 range to go 60 mph (where you state you have a heating problem) That's nothing for RPM, engine is hardly working, so I'd look at simple things first.

Lean carb and/or crappy tank of fuel. Possibly check optimum timing at those cruise speeds, make sure vacuum advance is working which should be adding 10-15 degrees at these light throttle cruise rpms on top of your total timing, for something in the range of 50 degrees give or take.
What kind of water pump/crank pulleys are you running? Could possibly change the ratio here up or down for better cooling performance. Lots of possibilities but likely a very simple solution.

[462ta]

had the car for 10 yrs just changed out all hoses and the bottom hose never had a spring in it, maybe the new hose is cheaper/thinner and it is collapsing can u get the springs aftermarket

[Formulajones]

Yeah you can get the springs and add them yourself. They even make stainless springs so they don't corrode like the old steel ones did. I recently had this problem on my truck. Original 10 year old hoses, never a problem (no springs in them) but figured it was due for a change. I get OEM GM hoses (still no springs installed) from the dealer to reinstall and immediately days later had a collapsed hose.

So yes, I think your theory of cheaper/thinner new hoses nowadays may hold some merit.

It used to be that any molded lower hose I bought 9 times out of 10 would have the spring in it already for added support. Didn't matter if I was buying for a ford, pontiac, or chevy. Now you buy hoses and I haven't seen springs in them for a dozen years now. They are getting cheap for sure. I now add them myself.

Not saying this is your issue but a possibility. Next time it happens I'd pull over quickly, leave the car running and pop the hood to have a look at the hoses, rev the engine etc... may be able to see something that way.

[Tom Vaught]

Agree, a spring in the lower tank hose might be the ultimate fix.

Have worked on other cars for people with the same issue/repair mentioned by FJ

Tom V.

[462ta]

break in the weather so took car for spirited hwy cruise all was good for many miles never got over 185deg so thinking hey maybe the thermostat worked but then it started to creep up again--heat soak maybe- same with hose maybe as hose gets hot it is not as ridged and collapses so that will be my next try

[462ta]

where are u guys getting the springs no parts places over here can get them

[steve25]

I made one once from a coat hanger formed around a pipe, was not photo worthy but it worked!
Just a side note, our government does not want us collecting rain water any more so keep your eyes peeled!
Yeah, you read right my friends, what next!

[Rugratman]

Timing not advanced up?

Check that hose. Those high flow pumps will do that to a weak hose, even if it is new. They get hot and soft.