The spiking i am talking about is before the Tstat opens. It climbs well above the 210 halfway mark before the tstat opens and drops down to 210.
I've never had another truck where i could "watch" the tstat open like that.
CK5
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Cooling System Overhaul - Stumped and Frustrated
- Thread starter dhcomp
- Start date
The spiking i am talking about is before the Tstat opens. It climbs well above the 210 halfway mark before the tstat opens and drops down to 210.
I've never had another truck where i could "watch" the tstat open like that.
I mean the same thing when coolant level is low...temp goes way high, then opens. Probably due to the t-stat not being in coolant, so coolant temp got higher while the thermostat was very slowly responding to increasing metal/air temps.
But I can't make a correlation in your case. Your coolant levels are obviously fine, and I can't think of a single reason the t-stat would not be sitting in coolant. This is where an air bubble is an issue, but ONLY until the t-stat opens.
For some reason a coolant flow issue keeps coming to mind in your case, but with all you have done and tried, I'm not sure what you haven't covered. Heater hoses are plumbed correctly, right?
But I can't make a correlation in your case. Your coolant levels are obviously fine, and I can't think of a single reason the t-stat would not be sitting in coolant. This is where an air bubble is an issue, but ONLY until the t-stat opens.
For some reason a coolant flow issue keeps coming to mind in your case, but with all you have done and tried, I'm not sure what you haven't covered. Heater hoses are plumbed correctly, right?
I've never replumbed them. manifold hard line, and soft line into the radiator tank.
ccarley
1/2 ton status
How's it been working with the high flow thermostat?
Got my BMW back on the road, so i haven't been commuting in it anymore.
Last few times i drove it, it kinda lived just over 210. Constant temp is about the same as it was with the other stat, but seems to be tougher to get it to climb.
My next tahoe trip will tell the real story.
Last few times i drove it, it kinda lived just over 210. Constant temp is about the same as it was with the other stat, but seems to be tougher to get it to climb.
My next tahoe trip will tell the real story.
So, the truck still heats up a bit. And, considering all the work i've done to it (new motor, cooling system, upgraded radiator), plus the amount of towing i'm going to be doing soon, i'd love to get this worked out.
Would some sort of intake leak, or a cracked intake case this issue?
In the last few years, the truck has idled really rough on startup, like it has a vac leak.
Even after doing the intake gaskets a few times, and then one final time on the new Crate motor, it still does this.
Sounds like a poorly tuned carb truck until it warms up.
Intake manifold is original as far as i know. Would some sort of internal or external crack cause my rough startup, and slight overheating issues?
Any other new thoughts on my situation?
Thanks guys!
Would some sort of intake leak, or a cracked intake case this issue?
In the last few years, the truck has idled really rough on startup, like it has a vac leak.
Even after doing the intake gaskets a few times, and then one final time on the new Crate motor, it still does this.
Sounds like a poorly tuned carb truck until it warms up.
Intake manifold is original as far as i know. Would some sort of internal or external crack cause my rough startup, and slight overheating issues?
Any other new thoughts on my situation?
Thanks guys!
does this lose coolant, and have you done a coolant system pressure test?
I know people sit there and go "oh, why buy a tool like that, I can figure it out from other symptoms!".. but there are reasons why such tools exist...
it may be rentable too...
I know people sit there and go "oh, why buy a tool like that, I can figure it out from other symptoms!".. but there are reasons why such tools exist...
it may be rentable too...
Its not common,but I have seen a few stock cast iron small block intakes crack under that tin shield that is pinned on the underside (that faces the lifter galley) ,also a few that cracked internally where the heat riser passages channel exhaust gases up under the carb to pre heat the air fuel mixture,and it lets the exhaust gases dilute the fuel/air mixture,makes it run lean,which also makes comburtion temps rise..
However,in all the cases of this I saw,the engines ran better after being started cold,and ran progressively worse as they heated up,probably because the cracks opened up more when hot,and leaned the mixture out..the engines had a stumble on acceleration like a bad accelerator pump,and pinged pretty bad,even with the timing retarded some from stock settings..when another intake was installed (aftermarket ones in most of the time),the engine ran beautifully..and many people threw parts at them and could never get them to run good or figure out why..
I would do what Ryoken said,borrow or rent a pressure tester and put it on the radiator and pump it up,then start it from cold and watch the gauge..if it starts rising suddenly about the same time the thermostat opens it could have a slight head gasket leak thats letting compression sneak into the coolant,but not let coolant get in the cylinder..this makes the coolant foam up and it cant cool the engine good when its foaming..
I recently got 2 Stant radiator tester kits given to me--friend found one complete in a cars trunk he was given to haul away for scrap,and he had another one cluttering up his tool box and has 3 more,so he was going to chuck them!..being a dumpster diver,I didn't let that happen..
I am hesitant to try using them on my old radiators though--might pop them and make a leak with my luck!..
shouldn't be an issue... just bring the pressure tester to just under cap pressure and let it sit, that's what it's getting to anyway at operating temp.. BUT if your not losing AF, and not overheating, really no point in "stressing" the system... 
Ive got a tester. Bought one to test on the old motor.
Should I test at operating temp, or cold?
Not losing much coolant, but may be losing a little bit.
Should I test at operating temp, or cold?
Not losing much coolant, but may be losing a little bit.
cold is fine... engine off, put it on, pump to appropriate pressure for your cap, let it sit 10 minutes.. check...
Got it. Good suggestion. Wondered when i'd use that damn tool again
Never dawned on me to check with the new motor.
I use it once or twice a month usually, it's a staple in my biz with all the crazy cooling systems I see...
FWIW if you lose pressure with the checker and it's not leaking, take the plugs out after losing the pressure, and turn the motor over. Coolant is either in the cylinders and will blow out, or it's in the crankcase.
What is the diameter of your crank and water pump pulley? I want to see if they are same as on my 89. I wander if they put smaller diameter pulleys in with the overdrive trans. Ever try driving around in high gear and not in OD. My burb runs around 2500 at 55 with the TH400 trans.
I'm running a high flow Meziere water pump and it actually runs cooler when it down shifts (3500+ RPM) to climbs steep hills then on light grade hills when it doesn't. Still it never seems to run hotter than 220. Normal driving semi-flat it runs around 190-200.
I do see a big spike when the thermostat opens but once it normalize on temp it stops. 190' tstat highflow. My truck seems to always run 10' hotter than whatever thermostat i put in it. I put my mechanical gauge in the intake near the thermostat I want to see the temp of the water leaving the block. This is more consistent then in the back of the cylinder head.
Do you have a bypass hose hooked up? most TBI trucks don't, at least the ones i have seen. Mine dose not.
I'm running a high flow Meziere water pump and it actually runs cooler when it down shifts (3500+ RPM) to climbs steep hills then on light grade hills when it doesn't. Still it never seems to run hotter than 220. Normal driving semi-flat it runs around 190-200.
I do see a big spike when the thermostat opens but once it normalize on temp it stops. 190' tstat highflow. My truck seems to always run 10' hotter than whatever thermostat i put in it. I put my mechanical gauge in the intake near the thermostat I want to see the temp of the water leaving the block. This is more consistent then in the back of the cylinder head.
Do you have a bypass hose hooked up? most TBI trucks don't, at least the ones i have seen. Mine dose not.
intake manifold gasket,auto tranny lines. automatic trannies always make them run hotter. timming. holes in grill to small. not enough air flow thru rad. my 77 has a solid mount fan no clutch. my 79 has a clutch and runs 20 degress hotter. i would think its the tranny making it run hot.
I just check my 89 pulleys -vs- my 93 1/2ton 350/4L60. all the pulleys seem the same size or at least so close you can't see it with a tape measure.
My meziere pump didn't make alot of difference on flat ground cooling but it sure did on the hill climbs. Like i said it will acually run cooler when it down shifts when climbing hills. I have not towed anything heavy yet with this combo,
So, this F*cking thread is back.
I have done little to the burb this winter except drive it.
It heats up here and there, but not bad. Haven't towed with it.
Finally pressure checked the cooling system today. Cold, its loses VERY little pressure. Haven't checked it hot yet.
Any other tips? High flow water pump?
Thinking of adding electric pusher fans to the oil and trans coolers.....
I have done little to the burb this winter except drive it.
It heats up here and there, but not bad. Haven't towed with it.
Finally pressure checked the cooling system today. Cold, its loses VERY little pressure. Haven't checked it hot yet.
Any other tips? High flow water pump?
Thinking of adding electric pusher fans to the oil and trans coolers.....
Are those meziere water pumps really $450?
I don't think i paid that for my radiator! Holy crap
Clearly, there has to be a solution for this.
I'm all good with slow towing, but heating up doesn't cut it.
WTF.
New motor, rad, total cooling system, still gets too warm.
Maybe i should have gotten the larger champion radiator.
Edit: for the 4th time.
This is making me nuts. I hate issues like this, that make me want to upgrade to a newer rig. I like working on my stuff, but sometimes, i just need it to work right.
Truck runs fine, and does great, pretty low maintenance recently (ssssssshhh, don't let it hear).
But, this issue is keeping me from being able to wail on it and be certain it will continue doing its job.
I don't think i paid that for my radiator! Holy crap
Clearly, there has to be a solution for this.
I'm all good with slow towing, but heating up doesn't cut it.
WTF.
New motor, rad, total cooling system, still gets too warm.
Maybe i should have gotten the larger champion radiator.
Edit: for the 4th time.
This is making me nuts. I hate issues like this, that make me want to upgrade to a newer rig. I like working on my stuff, but sometimes, i just need it to work right.
Truck runs fine, and does great, pretty low maintenance recently (ssssssshhh, don't let it hear).
But, this issue is keeping me from being able to wail on it and be certain it will continue doing its job.
Last edited:
how much is VERY little, and over what length of time did you leave it on?
