New radiator right? I just don't see the radiator being plugged. There would have to be significant debris to cause this, and weren't you seeing the same problems with another radiator?
CK5
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Cooling System Overhaul - Stumped and Frustrated
- Thread starter dhcomp
- Start date
my TBI 454 runs 208 all day long with a 195 in it..
That's interesting.
Yep, Radiator is new, and not rebuilt.
Hell, EVERYTHING is new.
Is it possible that my cooling system just isn't up to par for my demands?
What would running the wrong rotation water pump do to the system? Any chance that's what is going on?
Any chance of the water pump or crank pulley being wrong?
Like ryoken, my 454 with 195* t-stat runs under 205* all day. My mech auto meter gauge shows less than 10* cycle while running.
Like ryoken, my 454 with 195* t-stat runs under 205* all day. My mech auto meter gauge shows less than 10* cycle while running.
Crank pulley is original. As far as i know. Water pump is a ACDELCO251725 (251-725)
which, shows as the correct serp belt pump.
which, shows as the correct serp belt pump.
Drill an 1/8" hole in the thermostat and see what happens.
Martin
Martin
I would pull the thermostat just to see what that does. There are tons of opinions about doing that, but it will definitely take it out of the equation if its sitting on the seat next to you.
If you then see a fairly constant temp, whether high or low, then you need to investigate the thermostat.
Could be a housing problem.
If you still get the spikes, then either your cooling system is just not enough, or something else is happening.
At that point I would take a long hard look at the fan clutch.
There are schools of thought out there that say running without a thermo will cause a truck to overheat.
The idea is that the water flows through the radiator too fast to be cooled.
I have argued against that a few times, but cannot actually prove its wrong without doing lots of tests and experiments that I never was interested enough to do.
I do know that in every case where I pulled the thermo on a vehicle with an adequate cooling system, it ran cooler.
If you then see a fairly constant temp, whether high or low, then you need to investigate the thermostat.
Could be a housing problem.
If you still get the spikes, then either your cooling system is just not enough, or something else is happening.
At that point I would take a long hard look at the fan clutch.
There are schools of thought out there that say running without a thermo will cause a truck to overheat.
The idea is that the water flows through the radiator too fast to be cooled.
I have argued against that a few times, but cannot actually prove its wrong without doing lots of tests and experiments that I never was interested enough to do.
I do know that in every case where I pulled the thermo on a vehicle with an adequate cooling system, it ran cooler.
Yeah, I think that is an old wives tale. I have ran several engines with no thermostat in them at all.
Martin
Martin
You are running/testing with a stock-size radiator for your truck, with no additional load (Same CID motor, not towing, etc), right? If so, there is no reason there should be a capacity problem.
There have been a few threads on wrong water pumps, as I recall they tend to idle within spec, but ANY engine load and the temp skyrockets.
You cannot run water through the radiator too fast, that is somewhat simple physics. The hotter water (coolant) gets, the less it efficiently absorbs heat. The thermostat governs *minimum* coolant temp, the radiator and fan(s) control maximum. Longer time in radiator means longer time in engine. Cylinder wall temps are well above the boiling point of coolant, any increase in coolant time in the block induces localized boiling, which causes even more cooling issues.
I have done it myself, so I know what happens on my vehicles. Others say they have seen the opposite, that it overheats. It is possible that by removing the thermostat in some applications coolant flow patterns are changed because it's moving faster, or out of the motor easier in one location, so I won't discount their observations as just because I've not seen it, does not mean it's not possible. My old-school GM stuff though, runs cold with no thermostat.
Yep, testing in a stock configuration. But other than the delayed Tstat opening, it mostly stays at 200-210 without load.
It hasn't gotten way hotter until I tow with it.
Going to pull the Tstat tonight, and see what it does on saturday. Getting slightly frustrated with this problem....
It hasn't gotten way hotter until I tow with it.
Going to pull the Tstat tonight, and see what it does on saturday. Getting slightly frustrated with this problem....
Definitely take it for a spin with no t-stat, if it DOES act up without it, you don't want that to surprise you when you are towing. 
Going to be hell with the fuel injection, but for short term I don't think it will be that big of a deal.
If it will idle at 200-210 your fan SHOULD be good. I would be more suspect of fan if the temp wasn't a spike as it is.
Going to be hell with the fuel injection, but for short term I don't think it will be that big of a deal.
If it will idle at 200-210 your fan SHOULD be good. I would be more suspect of fan if the temp wasn't a spike as it is.
Definitely take it for a spin with no t-stat, if it DOES act up without it, you don't want that to surprise you when you are towing.
Going to be hell with the fuel injection, but for short term I don't think it will be that big of a deal.
If it will idle at 200-210 your fan SHOULD be good. I would be more suspect of fan if the temp wasn't a spike as it is.
I ran my 94 for a few months with no tstat, and that was basically the same motor.
Different cam/tuning, but still a TBI 350.
No issues, just warmed up slow.
I want my burb cooling system to be as bombproof as that old 94!
Already a HUGE thread on what should be a simple problem! But you've covered a lot. Temps towing before were bad, and not just spiking, right?
On the old motor, yes, i was seeing temps in the 3/4 gauge range, if not slightly higher.
That being said, i had a heavier boat 2 weeks ago, and saw higher than that on a shorter grade.
Before i messed with this truck, stock tires, stock 3.73's....hell, stock trans cooler, i never saw 3/4 on that gauge. maybe a hair over half, but that was it.
That being said, i had a heavier boat 2 weeks ago, and saw higher than that on a shorter grade.
Before i messed with this truck, stock tires, stock 3.73's....hell, stock trans cooler, i never saw 3/4 on that gauge. maybe a hair over half, but that was it.
Whats the radiator size on the '94 comparatively? You said it has no problems, and new or old radiator, the new one is getting hot anyway.
The spike thing may be thermostat, but I do not see the overheating while towing being the same issue. I've not heard of a thermostat partially sticking just enough to raise engine temp, but not so much as to overheat.
The spike thing may be thermostat, but I do not see the overheating while towing being the same issue. I've not heard of a thermostat partially sticking just enough to raise engine temp, but not so much as to overheat.
simple/obvious question: Are you 100% sure your not putting the t-stat in upside down?
No idea. it was a 94 blazer, stock radiator, alum with plastic tanks.
Yes, 100% tstat is correct direction.
Interesting radiator specs:
http://www.jcwhitney.com/1992-1994-...-radiator-new/p3038270d50294y1992-1994j1.jcwx 1994 Blazer
http://www.jcwhitney.com/1987-1991-...ment-radiator/p3044048d50332y1987-1991j1.jcwx 1991 Suburban
I'm sure those aren't correct in every case, I just did a quick check to find some numbers. Do the math, see what the cooling capacity % difference is in cubic inches. I did the math for my smaller radiator conversion, and it was something like a 20% reduction in radiator capacity.
http://www.jcwhitney.com/1992-1994-...-radiator-new/p3038270d50294y1992-1994j1.jcwx 1994 Blazer
http://www.jcwhitney.com/1987-1991-...ment-radiator/p3044048d50332y1987-1991j1.jcwx 1991 Suburban
I'm sure those aren't correct in every case, I just did a quick check to find some numbers. Do the math, see what the cooling capacity % difference is in cubic inches. I did the math for my smaller radiator conversion, and it was something like a 20% reduction in radiator capacity.
Hm. Mine's the 28x19. Maybe i need to go bigger. Just didn't want to have to modify anything to go to the wider mounts, when I replaced it.
To go to the Diesel 34x19, do i just move the brackets to the wider mount point?
To go to the Diesel 34x19, do i just move the brackets to the wider mount point?
