I have a GM V8 and no heat coming out. I checked the control valve and it moves up and down letting water through. I then put high pressure water inot the hose going in the heater core and it circulated through fine. What do you guys think? Truck not heating up enough? It has a new thermostat for 195. Maybe the coolant is hot enough? Im out of ideas.
Any ideas on no heat happening!
- Thread starter PortFJ62
- Start date
This site may earn a commission from merchant affiliate
links, including eBay, Amazon, Skimlinks, and others.
- Joined
- Apr 4, 2006
- Threads
- 162
- Messages
- 4,044
- Location
- Hillsboro, OR
- Website
- www.cascadecruisers.com
Before I tell you the answer to that question Matt, I'm going to see some pics of the new rig.
Maybe it's that Chebby engine? 
Kidding...
It could be that you have a defective thermostat. Take it out and test it in boiling water. Good luck!
Kidding...
It could be that you have a defective thermostat. Take it out and test it in boiling water. Good luck!
- Thread starter
- #4
I brought it to the meeting but you were a NO SHOW! Ill post some pics later sunday when the bumper swap is done. Oh yeah, I havent been able to pass deq. First because no cats, So I put cats in. Still no pass. Damn CO was to high. So now Ive had to send a spare ecu to AZ speed and marine to get a new program for the ecu to run the engine different. I have no idea about this stuff but the prevouis owner does and says it will work. Im gonna be screwed if it doesnt pass next time. Crossing my fingers.
If you open the thermostat housing and you discover the tstat is open, that's your problem. Thermostats open only when hot, so if you get no heat, it means that your tstat is open while the engine is cold.
Is the swap a new swap? If so, the hoses could be hooked up wrong and not allowing water to flow properly. If both your return and supply line from your heater core are hooked up to the manifold, for example, then that could be your problem too. Another common mistake is to hook up one end to the return inlet on a radiator and teh other end to a splice in the lower return hose.
No differentiation in pressure means no water flow through the core.
Does the truck warm up when you drive it? What does the heat gauge say?
Is the swap a new swap? If so, the hoses could be hooked up wrong and not allowing water to flow properly. If both your return and supply line from your heater core are hooked up to the manifold, for example, then that could be your problem too. Another common mistake is to hook up one end to the return inlet on a radiator and teh other end to a splice in the lower return hose.
No differentiation in pressure means no water flow through the core.
Does the truck warm up when you drive it? What does the heat gauge say?
verfity thermostat and proper coolant level first.
Get truck up to normal temp. Physically touch the heater hoses and make sure they are hot / warm. When you come across one that is not hot then most likley that will lead to the problem. Both heater hostes at the firewall should be hot. IS your heater control valve working?
Get truck up to normal temp. Physically touch the heater hoses and make sure they are hot / warm. When you come across one that is not hot then most likley that will lead to the problem. Both heater hostes at the firewall should be hot. IS your heater control valve working?
- Thread starter
- #9
All hoses are hot when the truck is up to temp. Yes the valve is working, I pulled the hoses off and checked. When I grab the hose going into the valve I can feel it pumping.
The v8 has been in for 16,000. Previous owner said he used the heat a few times and it worked fine, using the stock toy core. Only thing that was changed when the truck was sold to me was a new t stat. One to run the truck cooler, Im thinking thats gotta be the problem.
The v8 has been in for 16,000. Previous owner said he used the heat a few times and it worked fine, using the stock toy core. Only thing that was changed when the truck was sold to me was a new t stat. One to run the truck cooler, Im thinking thats gotta be the problem.
Waggoner5
SILVER Star
The thermostat is a 195 and is new. The truck runs within 10 degrees of the t-stat so I know thats working correctly. Just trying to save you some work.
Anything around 180 or better thermostat will put out some heat at the heater core. So all heater hoses are hot, the thermostat is good, you have full coolant, and the truck is running somewhere around 195. You can see this on the temp guage? Sounds like heater core may be the problem.
So, if he has flow through the heater core, the t-stat is working, and the fan is working what in the heater core would be or could be the issue? I would hate to tear into this thing to swap the heater core to find it to not be the problem.
Some insight would be great as I have been helping Matt get his old rig fixed and his new on on the road.
cliNt
Some insight would be great as I have been helping Matt get his old rig fixed and his new on on the road.
cliNt
Well... if you have flow through the heater core and both heater hoses are hot that feed the heater core. You should have heat! When I say both heater hoses are hot....I mean hot, not just warm to the touch.
And you are saying the truck temp is around 195 or so as verfied through the temp gauage and you are also saying the truck is full of coolant and that the heater control valve works.... all true?
Do you have any expectation that the truck has air in the cooling system?
The heater core could potentially be stopped up or have restricted flow through it. Basically heater cores are replaced when they leak or they become clogged up, like your radiator.
I assume your heater blower motor is working and its just blowing cool air, with the temp setting set to full hot?
I certainly would not replace the heater core on a LC until such time I had looked at all the other issues.
Other issues are..... bad water pump, clogged or restricted radiator, heater hoses setup wrong from engine swap, low coolant, faulty thermostat, bad heater control valve.
What temp is the truck running at now? Does the truck run fine except for the heater issue? Have you driven it extensively, and now all of a sudden no heat?
There is nothing else in the loop but the heater core if both heater hoses that are the return and intake for the heater core are hot, your fan blower motor is working, you are full of coolant, and the temp setting is set to full hot and blowing air at your feet, and the truck is at operational temp.
And you are saying the truck temp is around 195 or so as verfied through the temp gauage and you are also saying the truck is full of coolant and that the heater control valve works.... all true?
Do you have any expectation that the truck has air in the cooling system?
The heater core could potentially be stopped up or have restricted flow through it. Basically heater cores are replaced when they leak or they become clogged up, like your radiator.
I assume your heater blower motor is working and its just blowing cool air, with the temp setting set to full hot?
I certainly would not replace the heater core on a LC until such time I had looked at all the other issues.
Other issues are..... bad water pump, clogged or restricted radiator, heater hoses setup wrong from engine swap, low coolant, faulty thermostat, bad heater control valve.
What temp is the truck running at now? Does the truck run fine except for the heater issue? Have you driven it extensively, and now all of a sudden no heat?
There is nothing else in the loop but the heater core if both heater hoses that are the return and intake for the heater core are hot, your fan blower motor is working, you are full of coolant, and the temp setting is set to full hot and blowing air at your feet, and the truck is at operational temp.
the restriction theory related to the heater core is.....coolant may flow through the heater core but if its restricted the collant may only flow through a very small portion of the heater core or not be flowing through it hardly at all. Or the flow may be so small as to reduce the capacity of the heater core to become hot.
Waggoner5
SILVER Star
I did this conversion several years ago and put 16000 miles on the truck since. The truck runs fine cools fine and the heat has always worked fine. When Matt bought the truck I was unaware that the heater was not blowing hot air. The only things that have been changed from the original configuration is a new $750 Ron Davis radiator, new thermostat, and Evans coolant. The truck had been parked for quite a while previous to this heat issue, but the cooling system was flushed when the parts were changed. It is possible that there is air in the system causing the water flow issue to the core. This system has worked flawless for several years in this configuration so it must be core or air in the system related. Pic of the engine compartment.
not to thread hijack but... i guess you sold the 502 60 gary?
cruiser_guy
Out of Africa / North Africa
Backflush the heater core and see what happens. I had the heat go out on the '60 in the middle of winter on a drive through the Rockies. The shop backflushed the heater and all was well.
In some other vehicles, when you don't get heat but all else checks out, it is air in the system. So I would agree with the previous owner (who probably knows a thing or two about his old rig). Time to "burp" the cooling system.
Yes he did, he sold it to me!Without heat;p
that is an awesome rig! enjoy it!
and like several others have said I too am gonna say air in the cooling system.
