1990 Nissan Pickup - Overheating/No Heat

[Britches]

Hello,

I have a 1990 Nissan pickup. Right now it has no thermostat and runs no higher than the "C" on the temperature gauge. If the thermostat is installed, it runs hot. Here's a timeline of what's happened to it as well as what's been done to it:

1. Timing chain wore a hole in the timing chain cover causing the truck to overheat.
2. Timing chain cover was replaced and a new timing chain kit was installed.
3. Truck was overheating so we turned the heat on to help cool engine and no heat came out of vents.
4. New water pump and thermostat were installed.
5. Truck was still overheating and still had no heat so I had someone check for blockage in the lines and none were found.

I really want to get the thermostat installed so I can get it up to operating temperature. Why does it run hot when the thermostat is installed and why is there no heat?

Thanks in advance!

[junior3382]

First, Welcome to the forum.......

You may have two seperate issues here. First, if you install the thermostat, does it OVER heat? Or just raise back to normal temps? And if that is the case, why did you take it out? I am confused on this subject because in the begining you said W/O it the motor runs cold, yet at the end, you are saying it is overheating, and you want to put the thermostat back. Just needed some clarification there.

As for the heat, that could be completely unrelated. Regardless of the heat of the engine, if the heater core is junk, then you will not get any heat, as I have so rudely found out recently with my truck! So it is possible you may need a core.

But on a side note, how would a warn hole in the timing chain cover cause it to over heat? What is the motor you are running? Had it ever been in an accident? I mean it seems odd that it would just randomly start rubbing on the cover and not have something else have happened. Know what I mean?

I wish I could help more, but it seems I have more questions then answers for you bud. Sorry.

[crabtruck]

Since you have the overheat problem, my first thought on no heat would be air in the system. May want to flush the cooling system and while it's apart, directly flush the heater core to be sure it's not plugged. You didn't mention if it ever worked. You are sure it's overheating and not just a gauge problem ?

[Britches]

Originally Posted by crabtruck

Since you have the overheat problem, my first thought on no heat would be air in the system. May want to flush the cooling system and while it's apart, directly flush the heater core to be sure it's not plugged. You didn't mention if it ever worked. You are sure it's overheating and not just a gauge problem ?

Someone has burped the air out of the lines as well as blew air into the lines of the heater core. Are you saying the heater core needs to be flushed with water? Btw, yes, the heat used to work before the timing chain cover was breached. I am not 100% sure it's overheating as I have not temped the coolant itself, but why else would it go from "C" to indicating overheating when the thermostat is installed?

[Britches]

Originally Posted by junior3382

First, Welcome to the forum.......

You may have two seperate issues here. First, if you install the thermostat, does it OVER heat? Or just raise back to normal temps? And if that is the case, why did you take it out? I am confused on this subject because in the begining you said W/O it the motor runs cold, yet at the end, you are saying it is overheating, and you want to put the thermostat back. Just needed some clarification there.

Yes, when the thermostat is installed, it overheats.

Originally Posted by junior3382

As for the heat, that could be completely unrelated. Regardless of the heat of the engine, if the heater core is junk, then you will not get any heat, as I have so rudely found out recently with my truck! So it is possible you may need a core.

It is possible that the heater core went bad, but it worked fine before the timing chain cover was breached and all this started. It could be a coincidence, but I guess I'm thinking it's somehow related.

Originally Posted by junior3382

But on a side note, how would a warn hole in the timing chain cover cause it to over heat? What is the motor you are running? Had it ever been in an accident? I mean it seems odd that it would just randomly start rubbing on the cover and not have something else have happened. Know what I mean?

I wish I could help more, but it seems I have more questions then answers for you bud. Sorry.

There is a port that runs through the timing chain cover where coolant flows through. A timing chain guide broke so the timing chain began to rub up against the port where the coolant flows through. Once a hole was created, the coolant mixed with the oil and the truck began to overheat.

[Britches]

Someone suggested it might be a blown head gasket. What are you guy's thoughts on this?

[junior3382]

If the coolant mixed with the oil and still flowed through the system, then it is very possible that the sludge created worked its way into your core. I would listen to CRAB here and try flushing the whole system, and yes using water is better.

As for a head gasket, depending upon the extent of the damage done, it is possible the head gasket was affected, but beofre you tear all that apart, flush the system, and see if it is really overheating and not just the gauge. If that works, it will save time and money.

Also, are you sure you have the right thermostat? Some of them them open at different temps and it is possible the guy at the parts store sold you the wrong one. Not incredibly likely, but it has happened to me in the past with an alternator! He handed it to me and said "This is the one for your car!" and after two days, it burnt out! Turns out there was three different ones, depending on options, but the one he gave me was in stock! Personally, he was an idiot!

But not to get off point here, I am the kind of guy that will try hard not to spend money i do not need to. A flsuh and visual check is easier then replacing a core and head gasket, not to mention cheaper, so i would start there bud.

hope this helps.

[Britches]

Originally Posted by junior3382

If the coolant mixed with the oil and still flowed through the system, then it is very possible that the sludge created worked its way into your core. I would listen to CRAB here and try flushing the whole system, and yes using water is better.

As for a head gasket, depending upon the extent of the damage done, it is possible the head gasket was affected, but beofre you tear all that apart, flush the system, and see if it is really overheating and not just the gauge. If that works, it will save time and money.

Also, are you sure you have the right thermostat? Some of them them open at different temps and it is possible the guy at the parts store sold you the wrong one. Not incredibly likely, but it has happened to me in the past with an alternator! He handed it to me and said "This is the one for your car!" and after two days, it burnt out! Turns out there was three different ones, depending on options, but the one he gave me was in stock! Personally, he was an idiot!

But not to get off point here, I am the kind of guy that will try hard not to spend money i do not need to. A flsuh and visual check is easier then replacing a core and head gasket, not to mention cheaper, so i would start there bud.

hope this helps.

Thanks a lot for the help! I'm the same way you are: I don't want to spend money I don't have to. I'm going to have the core flushed and temp the coolant at the radiator cap and see if the gauge is off. Thanks again!

[Britches]

I'm not sure if this helps, but my mechanic said that both the lines going to the heater core are still cold even when the engine is overheating.

[junior3382]

Originally Posted by Britches

I'm not sure if this helps, but my mechanic said that both the lines going to the heater core are still cold even when the engine is overheating.

Then there is a blockage. They should warm up. and if there is a blockage, then there is your overheating problem too. A flush may not remedy this, you may have to pull all the hoses off and pray it is in one of those, and not in the motor