i just finished replacing the hg on my 7m-gte with a mls cometic hg, put a brand new water pump, new thermostat and put in a whole top end seal kit in. My problem is that when the car is warm the top radiator hose stays super hard and i get no heat in my car. I flushed the system and still nothing. When i drive my car it doesn't over heat at all and no smoke comes out of my exhaust but my car lacks alot of power. car is completely stock except for the manual boost control. im new to supra mania can someone please help
top radiator hose stays super hard but does not over heat and heater will not get hot
- Thread starter L.A.1983
- Start date
First of wrong place to post. If you post in the right place you can get help, always try a search first and troubleshoot your car, there could be a lot of different reasons why your heat isn’t working and why it lacks power. Make sure you put everything back together the correct way, check your thermostat, and post your questions in the correct place. Good luck.
Del, if your going to try to help him, don't do it half assed. You told him to post in the correct section, though you didn't tell him which one. He's new here, and may not be used to the layout of our forum, or any forum for that matter. Also, telling someone there are many reasons why a car may not be blowing heat, doesn't help.
Alright, lets get to the OP. Welcome to SM L.A. I moved your thread from the intro section, to the MKIII general section. You should get a little more help here. If the car is lacking power, a good first step is to check for codes, and go from there. Make sure you double check everything you touched. Check PVC hoses, EGR system, Intake manifold for leaks, and make sure there are no leaks between your AFM and the throttle body.
As far as the heater not working; With the car running and warm, turn your climate control down. Look at the heater control valve. (I forgot whether or not it's supposed to be up or down). Now turn your heater to the warmest setting. Look at the valve again. It should be in the opposite position. If it didn't move, it's more than likely your HCV. If it did, check your passenger side floor for wetness. If it's wet, it's your heater core. And have fun with that. Only took me 14 hours to change mine. Lol.
Alright, lets get to the OP. Welcome to SM L.A. I moved your thread from the intro section, to the MKIII general section. You should get a little more help here. If the car is lacking power, a good first step is to check for codes, and go from there. Make sure you double check everything you touched. Check PVC hoses, EGR system, Intake manifold for leaks, and make sure there are no leaks between your AFM and the throttle body.
As far as the heater not working; With the car running and warm, turn your climate control down. Look at the heater control valve. (I forgot whether or not it's supposed to be up or down). Now turn your heater to the warmest setting. Look at the valve again. It should be in the opposite position. If it didn't move, it's more than likely your HCV. If it did, check your passenger side floor for wetness. If it's wet, it's your heater core. And have fun with that. Only took me 14 hours to change mine. Lol.
all vacuum lines and everything were put back in place and my boost guage is reading 20 in./mg for vacuum suction which thats what it was reading before i replaced anything. there are no codes on the car other than a code 51 that comes on once in a while after i step on the gas at idle. the other thing ive noticed is a small exhaust leak where my exhast manifold is, i think the bolts where stripped and aren't making good contact with the head and manifold ( would that make my turbo act funny )?
If you have no heat and the hose is super hard. Im going to guess the coolant level is low and the reason it doest appear to be overheating is because the coolant is not in contact with the coolant temp sender.
Chances is the motor is overheating because its not flowing any coolant.
Put the car on oil change ramps turn the temp to 65, fan setting low, set to top vents, not defrost. Turn off the car and let cool down completely.
Then when car is cool take off radiator cap and pour in coolant until it is almost to the neck of the radiator. At this time check the heater control valve mentioned earlier. Its on the pass side and has heater hoses connected to it. It is mounted to the firewall almost directly behind the turbo.
Then start the car and turn the heat on full blast. Check the heater control valve after starting the car and turning on the heat and the actuator arm should be in the opposite position.
Then top off the coolant in the radiator until the car is warmed up or until heat is coming from the vents inside the car. At this time re install the radiator cap, pull off ramps and take for a short drive while monitoring the TEMP gauge.
Yes the manifold to head, or manifold to turbo, having an improper seal will effect turbo operation.
Chances is the motor is overheating because its not flowing any coolant.
Put the car on oil change ramps turn the temp to 65, fan setting low, set to top vents, not defrost. Turn off the car and let cool down completely.
Then when car is cool take off radiator cap and pour in coolant until it is almost to the neck of the radiator. At this time check the heater control valve mentioned earlier. Its on the pass side and has heater hoses connected to it. It is mounted to the firewall almost directly behind the turbo.
Then start the car and turn the heat on full blast. Check the heater control valve after starting the car and turning on the heat and the actuator arm should be in the opposite position.
Then top off the coolant in the radiator until the car is warmed up or until heat is coming from the vents inside the car. At this time re install the radiator cap, pull off ramps and take for a short drive while monitoring the TEMP gauge.
Yes the manifold to head, or manifold to turbo, having an improper seal will effect turbo operation.
i'll try that this weekend and post an update thanks for all the input, i didnt actually think people would even respond to my post but im glad you guys did. I love my supra and id hate to get rid of it
If the rad hose never softens when the car cools, your thermostat is installed facing the wrong direction.
Fix that quick!
The side with the spring faces into the water neck. The toggle valve should be at the highest point to permit air bubbles to pass. CUT OFF the toggle valve, doesn't do any good to obstruct flow.
If flipping around the thermostat isn't the fix, check back with us
Fix that quick!
The side with the spring faces into the water neck. The toggle valve should be at the highest point to permit air bubbles to pass. CUT OFF the toggle valve, doesn't do any good to obstruct flow.
If flipping around the thermostat isn't the fix, check back with us
thermostat is on the right way and the hose does get soft after it cools down i double checked it after you posted the comment thedave925 (thanks). im in the process of heli coiling my exhaust manifold and im geting low compression on the 5th cylinder every thing else reads 150 but one reads 135 so im checking the shims to see if they are within specs. when i took the head off to do the head gasket the valves looked fine so maybe its the shims or the valve seal that might be messed up?
thedave925;1538290 said:
You have got to be kidding me. Where the f*&% did you come up with that?
To the OP your "no heat" issue is definitely has something to do with the heater control valve. Either it is not getting signal, or is not opening, with signal.
when your car is running next, mess with the valve on the firewall to see if you can manually get coolant to flow. It is not exactly a simple system but if you just start messing with it (while understanding that you are trying to get coolant to flow into the cabin) i have a feeling that you will at least figure out how to make it work.
You can hear and feel the fan right?
the shims' job is to correct valve lash from the cam lobe to the lifter bucket, they will not have an affect on spring pressure to keep the valves seated.
Usually piston rings develop blow-by before valves start leaking. Try a bit of oil in the low cylinder to help the rings seal up, that should bring up your specs during compression testing.
like mkiiichip is saying, do something to ensure coolant flow through the heater core:
The valve mounted on the firewall to route coolant to the heater core, is referred to as Heater Core Valve or HCV.
The HCV has a vacuum diaphragm to actuate whether the lever is up or down. I think up is flowing. Either way, the diaphragm is sprung to the off position.
Unhook the rod from the diaphragm to the lever, that will allow easy manual movement without breaking valve.
EDIT: saw you checked the thermostat
How long did it take for the hose to deflate? Should be the normal few hours and not overnight.
What temperature is your thermostat? It should be 88*C (~195*F)
The thermostat is a one-way valve that would take forever to open up if the wick was facing the wrong direction, plus the water pump only circulates one direction and works best without obstruction
Think about how the head gets hot fastest, the wick is installed facing the head to open up fastest, and once open it allows the water pump to push some cooler fluid from the rad into the water neck past the thermostat through the head and into the block, past the pump and back to the rad to cool again.
Is there something wrong with that logic?
He just fixed a headgasket, ten minutes to check can save him hours of work and hundreds of dollars.
Good point, the fan is kinda important to push air past the heater core.
Usually piston rings develop blow-by before valves start leaking. Try a bit of oil in the low cylinder to help the rings seal up, that should bring up your specs during compression testing.
like mkiiichip is saying, do something to ensure coolant flow through the heater core:
The valve mounted on the firewall to route coolant to the heater core, is referred to as Heater Core Valve or HCV.
The HCV has a vacuum diaphragm to actuate whether the lever is up or down. I think up is flowing. Either way, the diaphragm is sprung to the off position.
Unhook the rod from the diaphragm to the lever, that will allow easy manual movement without breaking valve.
EDIT: saw you checked the thermostat
How long did it take for the hose to deflate? Should be the normal few hours and not overnight.
What temperature is your thermostat? It should be 88*C (~195*F)
The thermostat is a one-way valve that would take forever to open up if the wick was facing the wrong direction, plus the water pump only circulates one direction and works best without obstruction
Think about how the head gets hot fastest, the wick is installed facing the head to open up fastest, and once open it allows the water pump to push some cooler fluid from the rad into the water neck past the thermostat through the head and into the block, past the pump and back to the rad to cool again.
Is there something wrong with that logic?
He just fixed a headgasket, ten minutes to check can save him hours of work and hundreds of dollars.
Good point, the fan is kinda important to push air past the heater core.
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thanks again for all the advice guys ive been looking for heli coils everywhere and no one seems to carry them on hand everything has to be special ordered so i haven"t got my exhaust manifold on yet but id find a link that to help me understand the HCV a little better and how to bypass it. im definitely going to mess with it as soon as i get coolant back into the system, i just bought a new after market cx racing aluminum radiator so im waiting on that also. The heater blower is working so like you guys are saying it has to be the Heater control valve, i even flushed the system and the water poured out like crazy so it doesn't seem to be clogged. As for the radiator hose it stayed hard while the car was warm but 2 hours later it would be normal again. Car still doesn't over heat but radiator hose shouldnt be that hard. and im doing to try the oil in the cylinder to see if it raises compression. ill let you know what i come up with in a couple of days once i get it put back 2gether
Combustion chamber pressure leaking into the coolant passages (HG that is not sealing properly, warped or cracked head or block deck) would possibly cause the hose to be hard. Was the head and block machined properly to accept an MLS gasket? Perhaps a leakdown test is in order for the #5 cylinder. While at idle are there bubbles in the coolant? What is the temp of the upper radiator hose as compared to the lower hose?
thedave925;1539265 said:the shims' job is to correct valve lash from the cam lobe to the lifter bucket, they will not have an affect on spring pressure to keep the valves seated.
Usually piston rings develop blow-by before valves start leaking. Try a bit of oil in the low cylinder to help the rings seal up, that should bring up your specs during compression testing.
EDIT: saw you checked the thermostat
How long did it take for the hose to deflate? Should be the normal few hours and not overnight.
What temperature is your thermostat? It should be 88*C (~195*F)
The thermostat is a one-way valve that would take forever to open up if the wick was facing the wrong direction, plus the water pump only circulates one direction and works best without obstruction
Think about how the head gets hot fastest, the wick is installed facing the head to open up fastest, and once open it allows the water pump to push some cooler fluid from the rad into the water neck past the thermostat through the head and into the block, past the pump and back to the rad to cool again.
Is there something wrong with that logic?
He just fixed a headgasket, ten minutes to check can save him hours of work and hundreds of dollars.
If the shims are out of spec too thick it could hold a valve open.
A thermostat isnt a one way valve. Its a thermally controlled valve. Theres no direction of flow to a thermostat.
The Thermostat could probably only fit in one way on a 7m. Also the coolant flows top to bottom on the radiator. Out of the thermostat housing and into the water pump.
http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?Section=CO&P=2
The thermostat goes in the way it does so the heat from the motor is in contact with the thermostat mechanism. When it opens the water is flowing from the motor over the thermostat keeping it up to date with the waters temp so it can properly regulate. If the flow was the other way around it would be getting flow of cool water from the radiator causing the valve to close.
Thank you for the correction on the circulation of flow from the water pump.
I still stand by the thermostat being a valve nonetheless
Thats a great reason to check valve lash if it the head really was that stripped down for removal during the headgasket change.
How often/hard is it to fry a valve or seat on these engines?
I still stand by the thermostat being a valve nonetheless
Thats a great reason to check valve lash if it the head really was that stripped down for removal during the headgasket change.
How often/hard is it to fry a valve or seat on these engines?
Correct, a thermostat is a valve. It's a thermally controlled valve. It regulates flow regaurdless of direction.