Running Hot?

[McCSquare]

Physics lesson aside... why do I want to pull the T-stat? What do I learn from that?


All that discussion about running hotter without a t-stat really only applies to engines that are already exhibiting problems - or subjected to extremely heavy duty usage.

For a normal daily driven car that has no apparent problems with the cooling system, removal of the thermostat will allow unrestricted flow of coolant through the radiator. This will result in longer warm up time and cooler operating temperature under low loads.

You know that your t-stat is at least partially opening because you can see flow out of the radiator cross-flow tubes and into the cool side tank.

But, by design, thermostats vary the flow rate like a valve. They don't open and close fully and stay that way,they are in a constant state of flux. They react to the coolant temperature that is in contact with the wax-filled cylinder. However, as simple and dependable as they are, they are not infallible.

Yours may not be opening fully. If you don't want to drive without one, just take it out, throw it in a pot of water and crank up the heat.

It should be starting to crack open when you can see vapor bubbles start to form and break free of the pan.

By the time the water is boiling vigorously the t-stat should be wide open - you should be able to esily pass a pencil through the gap between the seat and disc of a wide open t-stat.


BTW - you do have a shroud installed between the radiator and the fan - correct?

I do have the radiator shroud installed. I'll try pulling the t-stat. If I need to replace it, do I need a 140* or 180* t-stat?

I've been looking at radiators, and it seems like I can get some aluminum ones with plastic side tanks for about $200 which doesn't seem awful. I have a feeling this is the original radiator and it does look pretty corroded from what I can see. I really hate throwing parts at this truck, but it doesn't seem like a horrible investment.

I need to double check on the head gasket concern. I'm not confident I didn't see bubbles. But it is very hard to see down in there. Any other signs I can check for? The engine doesn't look overly dirty and the vacuum and plugs look pretty good.

 

[MrMarty51]

I do have the radiator shroud installed. I'll try pulling the t-stat. If I need to replace it, do I need a 140* or 180* t-stat?

I've been looking at radiators, and it seems like I can get some aluminum ones with plastic side tanks for about $200 which doesn't seem awful. I have a feeling this is the original radiator and it does look pretty corroded from what I can see. I really hate throwing parts at this truck, but it doesn't seem like a horrible investment.

I need to double check on the head gasket concern. I'm not confident I didn't see bubbles. But it is very hard to see down in there. Any other signs I can check for? The engine doesn't look overly dirty and the vacuum and plugs look pretty good.

Try running without the T-stat and see how it does,get a 195 thermostat.
There is bigger,better radfiators out there that will increase the cooling capacity.not that the originals are that bad.I just like the extra room.LOL
On the plugged radiator core,I had that happen on a ferd of a friends,after I had put now heads on His 302,He swore it was My workmanship and after it was all said and done,after expalaining it was the corer,many times over,and,He then trook the radiator in to a shop and sure enough,it would`nt flow for crap,He sure was eating humble pie until I handed Him the bill.He ****** exploded,to which I calmly explained that I had spent "WAY TOO MANY HOURS ON THAT PIECE OF **** FOR HIM TO NOT HAVE TO GIVE ME RESTITUTION FOR HOURS SPENT CHASING WHAT HE SAID WAS MY ******".
He paid.

 

[McCSquare]

So lets assume I need a new radiator...

I have the factory radiator with auto trans cooler in it, as well as a http://www.summitracing.com/parts/hda-678 in series.

It looks like I can spend anywhere from $90-400 for a replacement. What is the best bang for the buck? What fits the best?

RockAuto $145 - http://www.rockauto.com/catalog/moreinfo.php?pk=272029&cc=1299708

RockAuto $275 - http://www.rockauto.com/catalog/moreinfo.php?pk=534264&cc=1299708

Summit $390 - http://www.summitracing.com/parts/gri-8-70013/media/images/year/1984/make/chevrolet/model/k10

 

[MrMarty51]

So lets assume I need a new radiator...

I have the factory radiator with auto trans cooler in it, as well as a http://www.summitracing.com/parts/hda-678 in series.

It looks like I can spend anywhere from $90-400 for a replacement. What is the best bang for the buck? What fits the best?

RockAuto $145 - http://www.rockauto.com/catalog/moreinfo.php?pk=272029&cc=1299708

RockAuto $275 - http://www.rockauto.com/catalog/moreinfo.php?pk=534264&cc=1299708

Summit $390 - http://www.summitracing.com/parts/gri-8-70013/media/images/year/1984/make/chevrolet/model/k10

I got the stock replacement for My 93 from NAPA,same cooling capacity as the original,but,to Me,more is better if it is affordable.

 

[McCSquare]

I got the stock replacement for My 93 from NAPA,same cooling capacity as the original,but,to Me,more is better if it is affordable.

I was curious about the ideal construction...

Aluminum/Plastic

All Aluminum

Brass/Copper

Etc.

Benefits? I'd think all aluminum would be weight and corrosion resistance. But I don't really care about weight that much. What about the plastic end-tanks? Is that crap?

 

[MrMarty51]

Plastic end tanks is ok,if there is a brass/copper without the plasdik,that would be the best,In My Opinion anyhow.
Maby somebody else`ll kick in with some different and better infurmation.

 

[philjafo]

I used an aluminum one with plastic endcaps from a 91 in my 78, same width but about 2 inchs shorter. I just had to put a spacer under it and it cools the motor fine holds steady right at 200*. BTW had to use the newer style rad for the oil cooler in the driver side tank.

 

[87sierra]

okay maybe nobody thought of this or i missed it but did he not say he had a bad gasket on the coolant tube going into the engine and the coolant cap was bad so wouldnt that mean he has air in the cooling system

he also stated he had a bored 350 depending on the bore it could have weakend the cylinder walls and caused a small crack and is letting combustion gas into the coolant

 

[MrMarty51]

OH YES,and it was also explained that He shoud get all possibilities checked out afore He started throwing money atit.

 

[McCSquare]

okay maybe nobody thought of this or i missed it but did he not say he had a bad gasket on the coolant tube going into the engine and the coolant cap was bad so wouldnt that mean he has air in the cooling system

he also stated he had a bored 350 depending on the bore it could have weakend the cylinder walls and caused a small crack and is letting combustion gas into the coolant

I replaced the coolant cap and the water neck gasket. Neither should be leaking now. There is no overflow bottle installed yet.

If this motor is cracked I might lose my mind. This truck will officially be a lemon. How can I determine definitively if I have exhaust gases in my coolant? I'm not going to pull the head on a hunch, nor do I want to put a radiator in a junked vehicle.

 

[MrMarty51]

I replaced the coolant cap and the water neck gasket. Neither should be leaking now. There is no overflow bottle installed yet.

If this motor is cracked I might lose my mind. This truck will officially be a lemon. How can I determine definitively if I have exhaust gases in my coolant? I'm not going to pull the head on a hunch, nor do I want to put a radiator in a junked vehicle.

On these cross flow radiators it can sometimes be hard to discern if there is a combustion leakeage problem,in that, there is always some bubbles flowing with the coolant,but,if there is an excess of bubbles then there could be a problem,if it starts to pushing a LOT of bubbles then definetely expect that there is something wrong with a head{s} or a head gasket{s}.
That 302 Ford that I had such a problem with,the way I determnined that it was the radiator is,that,upon starting the engine,almost immediately,the top radiator hose got hard,to the point that I could hardly squeeze it.If there is an excess of white,sweet smelling prestone coming out of the exhaust then there is a problem with the head or gasket.If the exhaust has a raw smell to it,loike exhaust does,then chances are that the head or gaskets is OK.
There is a kit that can be purchased that detects combustion gasses coming through the coolant system,but,those are designed mainly for diesels and I do`nt know how well they would work on a gasoline powered engine,those kits are somewhat expensive too.
Like I stated before,the cheapest route to go would be to drain the cooling system and take Your radiator to a reputeable shop where they have the equipment to do a "Flow TRest" on Yopur radiator and that trest would determine one of two things,either that the radiatror is the problem,or, thjat it is not the problem.

 

[chengny]

How can I determine definitively if I have exhaust gases in my coolant?

There are testing devices but they are (by their own admission) about 90% accurate.

If you have an air compressor pull the plugs one at a time and apply compressed air to each cylinder. Have the thermostat housing open and watch for bubbles - it'll be apparent right away if you have combustion space to coolant system leakage.

I really doubt it's your radiator - don't buy a new one yet. Radiators don't just all of a sudden lose their heat exchanging capabilities. That happens over a long period of time and you recently flushed yours - also you have ascertained a good flow rate by looking down into the cool side tank. If you can see coolant coming out of the ends of the tubes the water side of the radiator is not fouled.

The water pump is moving the coolant - again you see that in the outlet tank.

Did you pull the thermostat?

Other than checking the coolant level and electric fan operation, removing the thermostat (either to test the t-stat itself, to see how hot the motor runs without one or simply replace it) is generally the first step in troubleshooting a problematic cooling system.

 

[MrMarty51]

How can I determine definitively if I have exhaust gases in my coolant?

If you have an air compressor pull the plugs one at a time and apply compressed air to each cylinder. Have the thermostat housing open and watch for bubbles - it'll be apparent right away if you have combustion space to coolant system leakage.

Good one.
I will have to remember that one,if I ever run across a suspected head/gasket leakage problem.

 

[McCSquare]

How can I determine definitively if I have exhaust gases in my coolant?

There are testing devices but they are (by their own admission) about 90% accurate.

If you have an air compressor pull the plugs one at a time and apply compressed air to each cylinder. Have the thermostat housing open and watch for bubbles - it'll be apparent right away if you have combustion space to coolant system leakage.

I really doubt it's your radiator - don't buy a new one yet. Radiators don't just all of a sudden lose their heat exchanging capabilities. That happens over a long period of time and you recently flushed yours - also you have ascertained a good flow rate by looking down into the cool side tank. If you can see coolant coming out of the ends of the tubes the water side of the radiator is not fouled.

The water pump is moving the coolant - again you see that in the outlet tank.

Did you pull the thermostat?

Other than checking the coolant level and electric fan operation, removing the thermostat (either to test the t-stat itself, to see how hot the motor runs without one or simply replace it) is generally the first step in troubleshooting a problematic cooling system.

I pulled the thermostat. I will give it a longer test drive, but it seemed to be running cooler. The thermostat looks fine, but I didn't try putting it on the stove.

I'm to try that trick with the air compressor you suggested. I still am nervous that I might also have a blown head-gasket.

 

[chengny]

"I still am nervous that I might also have a blown head-gasket. "

So am I - for you.

As someone noted in post #5:

Spikes in temperature indication (that can't be attributed to coolant system components) are often caused by combustion gasses in the coolant - due to a head gasket failure.

But on the upside, you have not made any mention of the #1 symptom. H/G failure between the combustion spaces and coolant system will almost always produce white smoke (actually vaporized coolant) at the tailpipe.

Another plus - there hasn't been any noticable loss of coolant - correct?

As far as checking a t-stat for proper operation by just holding it in your hand and looking at it ... I don't know how to respond to that.