Howdy folks! well, I've got an issue that maybe someone can help me with. Situation: 350TPI/700r4/4th gen 3.42 rear is the set up. All stock except for headers and some suspension components. Car starts fine, does have some surge when warm. I've noticed that if you baby the car and kep it under lets say 2500rpm, it does fine as car as the cooling system goes. If you get on it, the temp SHOOTS up from ~180-195 to 230-240 within a VERY few seconds. The h2o pump works good, no loss of coolant, fins on radiator are not bent, the air damn is gone BUT i have more than enough flow of air (I'm not an idiot and I know what I'm talking about) . Timing is good and there are no other apparent issues (hinse writing this page!!) My goal is NOT to have to pull the heads off and check the gaskets for blockages...

Check for a collapsing radiator hose.

Rog...

Both the top and bottom hoses are collapsing with you give it some go-juice... Gonna check to see if air is in the system and if not, then i'm going to replace the hoses... if so, ill fill it up and get another reading in a bit!

They're both collapsing? And you're not losing coolant from anywhere?

was abit of air in the system, filled it back up and the bottom hose is still collapsing bad. Still gonna replace them both just cause I can...

Flush cooling system. There may be a blockage somewhere causing this.
Pressure test.

Also, your cap may be bad and not holding pressure on the system.



But first, read this: http://automotivemileposts.com/autob...dhosecoil.html

Is the clutch is the mechical fan good? Is it pulling air across the rad?

Start there.

Never seen a top hose collapse before, as it's not on the suction side of the pump??

Fix the known stuff first - both hoses and air dam. Make sure the new bottom hose has a spring. Then rad cap and tstat cuz they're cheap. And go from there.

to get air all the way out,loosen the cap start car warm it up,and let tstat open and squeeze the top hose for a few secs to push bubbles out fill coolant and re check.

i replaced both hoses and the cap. I'm going to flush the system this weekend and see what that does... I'm also going to put an air dam on it next week ad put new fans on it. (they are electric fans)..

Yes both of the hoses were being sucked down. I'd never had that happen to the top before but on the bottom i have. Next step if all of this doesnt work is a nice 4 custom 4 core with an electric pump... I hope all of this is going to work or imma put a 7.62x54r in about 200 places

oh yea and i'm putting a 160* t-stat in it tomorrow as well

Well...it's your money. -_-



Hope it works.

why???

the lowest thermostat I run is 180 and that's in my LT1 4th gen

depends on what your setup is with thermostat,lower temps for carb cars,and older engines,also heat decreases power

Wouldn't that decrease the atomization of the fuel if it ran colder?

Only if it was truly cold, but a "cold" thermostat temperature is still plenty warm for atomization.

just because your temp guage says 160-180 the intake is still alot higher.but lower thermostat gives less chances of vapor lock,and frees up some extra power,and engines just seem to run happier cool.coolant temp is just the amount of heat being transfered to the coolant

Yea man, I've always run 160*s in my cars.. now in boats thats a diff story... I run a 180 in it but thats a diff kind of system. I've never seen an engine hate a 160, only love them... Do a dyno comparison for HP/TQ changes if you have the resources... cooler engine = longer life also... I've prolly built around 200 engines btw...

The engine itself doesn't care about 160, the control system does.

160-170*F is plenty hot for an OBDI GM control system. The 97 OBDII 350 Vortec in the Express van even has a 170*F in it without issue.

Running a gm efi engine at 160* is equivalent to running a carb engine w/ the choke half closed.

I have been running my 89 formula 350 with a 160deg t-stat (with proper fan switch) since 91..
It sure dosen't feel like the choke is half closed at 200mph plus or driving around.. car runs 160-165 no matter what I do with it.(stock rad and fans)
The water temp in these cars is just fine at 160.
The 02 is just fine with your water temp at 160.
If your a cold person and drive in the winter you may not b fine with a 160.
Fuel needs to be cold until it enters the combustion chamber..
you cant change the exhaust temp with a T stat nearly enuff to matter.
Its your timing, plugs and fuel that will affect exhaust gas temp.
Even then your running a heated 02 anyway right?

running 1/2 choke??? not quite man... anything above a 180* stat is way too hot... A performance engine will get peak HP (if ur set up is right) with cool iron (or alum), cold air, cool fuel and warm oil...

the cooler you keep it the longer it will last and the better it will run period

This is all funny to me. Do you think that when you're running a car hard that the temp is gonna stay at 160. The t-stat rating doesn't give you the max temp. It gives you the minimum temp. On a street car your probably losing 4-5mpg running at that temp. The oil doesn't get hot enough to burn off any moisture. Plus the the walls of the cylinders have less fuel on them, less of a chance of getting fuel in the oil.
These reasons are why newer engines can go 200k & show no cylinder wear, & older engines that ran carbs always have oil burning problems at 75k.
Running 190-200* going down the road is not overheating, period.