What did I do wrong?

[dlf60]

I have just replaced the head/head gasket/etc on my 89 Supra turbo and have a few issues that I would like some guidance on, please. I installed a remanufactured head, with a Toyota head gasket and ARP head studs, torqued at 80ft lbs. Since then, I have minimal coolant flow, the coolant temp gauge does not work at all, as well as the boost gauge. I have changed the coolant temp sensor, pigtail (as well as two other connectors on the water outlet) I verified voltage to the grn/yel wire and continuity between the brn wire and battery gnd. I checked that the sensor resistance changed when submersed in hot water. I reassembled all these components as well as a new Toyota thermostat and ran the car for approx 30 min. (the front end was elevated) with the rad cap off and varying engine RPMS about every 5 min. I do get heat and the upper rad hose is warm but I see minimal movement of the coolant in the radiator. The engine is running/idling smoothly and quietly and there are no signs of any leaks. I did not notice the fact that the boost gauge was not working until later. I know that air in the cooling system could be an issue but I thought running it with the front end elevated would have eliminated that? I am puzzled about the boost gauge as I thought that was driven by manifold vacuum? ( I see reference to a turbo pressure module?) Did I screw up the head gasket install or damage the head (or was it warped to start with.....I did not check it prior to install as it was professionally rebuilt)? Both of these gauges did work correctly before I removed the head. Any guidance you could provide me would be greatly appreciated.
Thank you

[Jeeves]

Originally Posted by dlf60

I have just replaced the head/head gasket/etc on my 89 Supra turbo and have a few issues that I would like some guidance on, please. I installed a remanufactured head, with a Toyota head gasket and ARP head studs, torqued at 80ft lbs. Since then, I have minimal coolant flow, the coolant temp gauge does not work at all, as well as the boost gauge. I have changed the coolant temp sensor, pigtail (as well as two other connectors on the water outlet) I verified voltage to the grn/yel wire and continuity between the brn wire and battery gnd. I checked that the sensor resistance changed when submersed in hot water. I reassembled all these components as well as a new Toyota thermostat and ran the car for approx 30 min. (the front end was elevated) with the rad cap off and varying engine RPMS about every 5 min. I do get heat and the upper rad hose is warm but I see minimal movement of the coolant in the radiator. The engine is running/idling smoothly and quietly and there are no signs of any leaks. I did not notice the fact that the boost gauge was not working until later. I know that air in the cooling system could be an issue but I thought running it with the front end elevated would have eliminated that? I am puzzled about the boost gauge as I thought that was driven by manifold vacuum? ( I see reference to a turbo pressure module?) Did I screw up the head gasket install or damage the head (or was it warped to start with.....I did not check it prior to install as it was professionally rebuilt)? Both of these gauges did work correctly before I removed the head. Any guidance you could provide me would be greatly appreciated.
Thank you

First off, it's rare 'er for a Toyota OEM Thermostat to fail, but it's not unheard of. However, if you're getting air bubbles out of the radiator cap, and it's showing flow, I'd say it's working. The other thing to watch out for, from personal experience, is there are two coolant temp sensors with the same plug type. One reports to the ECU, the other reads to the gauge (or something to that effect). If you swap them, the gauge won't read at all, swapping them back made the gauge work immedately, appearantly swapping them didn't damage anything. Running it with the nose elevated is called burping the cooling system, and as per what you've done that shouldn't be a worry.

Boost gauge is unrelated. There is a black box on the drivers side, strut tower. It's black, and is about a two inch rectangle, it also has a black vacuum running to it from the intake manifold, and some wires running out of it. This is the boost sensor for the stock ecu and gauge. My guess is that it's not conected to something. They don't generally flat out quit working.

[dlf60]

Thank you for your help Jeeves. If you don't mind, I have a couple more questions. First I do not have coolant flow. My assistant told me there was but when I checked again I see none. The thermostat is the second Toyota thermostat installed as I thought the first was the wrong part. (The car originally had an aftermarket thermostat which was physically smaller and offset from the center). Maybe I should reinstall the old thermostat? Could it still be air in the system preventing flow? Coolant overflowed out of the radiator a few times so it was assumed that all the air had been purged. Is there a different way to purge the air or do I have a more serious problem?I see what you are saying about the connectors for the coolant sensor/gauge sender. I believe that I have them correct due to the length of the wires but just to verify.....The two sensors are different sizes. On my car, the connector on the top of the water outlet goes to the larger of the two sensors. Is this the one for the gauge? ( Due to multiple broken wires, I used a connector/sensor combo from a different 7MGTE and it is not the same as the original. Is the same type as on the cold start injector). On the boost gauge nothing on the sensor had ever been touched and it is all still intact. As that is unrelated to the coolant issue, I will chase that problem later. Thanks again for your help.

[dlf60]

Thank you for your help Jeeves. If you don't mind, I have a couple more questions. First I do not have coolant flow. My assistant told me there was but when I checked again I see none. The thermostat is the second Toyota thermostat installed as I thought the first was the wrong part. (The car originally had an aftermarket thermostat which was physically smaller and offset from the center). Maybe I should reinstall the old thermostat? Could it still be air in the system preventing flow? Coolant overflowed out of the radiator a few times so it was assumed that all the air had been purged. Is there a different way to purge the air or do I have a more serious problem?I see what you are saying about the connectors for the coolant sensor/gauge sender. I believe that I have them correct due to the length of the wires but just to verify.....The two sensors are different sizes. On my car, the connector on the top of the water outlet goes to the larger of the two sensors. Is this the one for the gauge? ( Due to multiple broken wires, I used a connector/sensor combo from a different 7MGTE and it is not the same as the original. Is the same type as on the cold start injector). On the boost gauge nothing on the sensor had ever been touched and it is all still intact. As that is unrelated to the coolant issue, I will chase that problem later. Thanks again for your help.

[Jeeves]

Originally Posted by dlf60

Thank you for your help Jeeves. If you don't mind, I have a couple more questions. First I do not have coolant flow. My assistant told me there was but when I checked again I see none. The thermostat is the second Toyota thermostat installed as I thought the first was the wrong part. (The car originally had an aftermarket thermostat which was physically smaller and offset from the center). Maybe I should reinstall the old thermostat? Could it still be air in the system preventing flow? Coolant overflowed out of the radiator a few times so it was assumed that all the air had been purged. Is there a different way to purge the air or do I have a more serious problem?I see what you are saying about the connectors for the coolant sensor/gauge sender. I believe that I have them correct due to the length of the wires but just to verify.....The two sensors are different sizes. On my car, the connector on the top of the water outlet goes to the larger of the two sensors. Is this the one for the gauge? ( Due to multiple broken wires, I used a connector/sensor combo from a different 7MGTE and it is not the same as the original. Is the same type as on the cold start injector). On the boost gauge nothing on the sensor had ever been touched and it is all still intact. As that is unrelated to the coolant issue, I will chase that problem later. Thanks again for your help.

Ok, so here's a simple test. Pull out the thermostat. see if you have flow. I know there are ways to pressure bleed air outta the system, but I've never used this method so I don't know much about it.
You can also attach a water hose (like, from a faucet) to the primary coolant lines and try to push water through (without having the thermostat in) the engine itselg. Coolant (water) should flow freely and w/o any real stops. If you attach the hose, and don't get water back out, you've got a block somewhere. Air pockets won't stop flow by themselves.

As for the connectors, the two connector that looks like a cold start injector connector is not a temperature sensor for anything I know of. That's been broken on my car since the day I've bought it, and it's never stopped anything from working. The temperature sensors that are important for this instance, are single wire, spade connectors. There's one down under-ish the power steering reservoir and one on the thermostat housing. I can't remember which is which.

[sbettencourt]

the head gasket can be placed backwards. the gasket has smaller holes at the front to force coolant the the rear of the head. make sure u have coolant in the block, remove the upper rad hose from the rad, start the engine coolant sould flow out. if not check water pump.