2004 Corvette LS1; Conversion: PUt in 1956 Chevy.

Well, during warmer weather, I've been thinking my LS1 is running pretty cool. Or, my thermostat was off.

I purchased a laser temp gun, and found this:

- Temp reading at guages: 175
- Temp reading using laser at copper Cool Flex upper radiator hose: 195
- Temp reading at brass heat sensor at rear of passenger head: ~ 165

Let engine run a while until fan comes on
- Temp reading at guages: 190
- Temp reading using laser at copper Cool Flex upper radiator hose: 208
- Temp reading at brass heat sensor at rear of passenger head: ~ 185

Based on above, I decided my 195 thermostat was working properly.

Now, I find that the engine is very slow to warm up.

And tonight, it is 49 outside, and I went for a drive. The temp reading at my guage inside never reached 175. In fact if I had the heater on full, the reading would drop to just above the C on the guage.

I pulled in my garage, and took these readings:

- Temp reading at guages: below 175
- Temp reading using laser at copper Cool Flex upper radiator hose: 167
- Temp reading at thermostat housing on front of engine: 122

By the way, my radiator is a Griffin 56 Chevy style radiator. The fan had just been disconnected before the drive from running any time the heat is on, so teh fan was not operating. (speaking of the engine fan).

By the way, I have my steam port blocked. I just read that is not a good idea, so I suspect I'll be trying to change that.

What do ya'all think?

 

REgarding the thermostat: Just got back in from another drive,and that TSTAT must be messed up. Runnign very cold when driving 55. I'm going to pull it and check it out.

 

Sounds like it's stuck open or something.

 

Current status is: I pulled the thermostat last night, and tested it. Put it in water on the stove, and used a temp gun to watch temp when it opens. It works fine.

I called S&P and talked to Mark. Someone said something about the LS1 water direction being reversed, and I got to wondering if I was supposed to hook my radiator hoses opposite of what seemed normal.

Mark said the LS1 does NOT reverse flow the water. He also thinks it is running cool because of having the steam vents closed. That seems odd to me. I can't imagine that causing it to run cold.

Anyway, I have ordered some steam vent adapters to put on the heads and plan on venting to the water pump. I guess I'll know before too long.

 

Just so you know, ours runs pretty cool as well. Part of our problem is that the radiator cools too efficeintly now that it is vertical and has a HUGE opening in front of it. Our scanner says the engine runs at about 192degrees, and it takes alittle while for it to warm up. We also noticed that it didn't run very well the first time it was exposed to cooler temps, but the computer must have learned what to do when it sees low IAT readings as it started running better after a while.

 

Mine also runs very cool, most of the time cruising the gauge will be @ 175 and the computer will read it as 190.

Bill

 

Does it go to C when driving in below 50 degree weather, and put out luke warm from teh heater? Having no heat is not good.

Do you have the Steam Vents hooked up?

 

on the drivers side plug i have a mechanical thermostat, it reads 190. i have the ls1 temp sensor on the passenger side plug- it reads 205. im guessing the drivers side is reading temp of the coolant that just entered the block and the passenger side is the coolant leaving the block temp

edit: i use to have a electric temp guage hooked up on the drivers side, but when it was saying 190 i thought it was messed up. so i swapped it out with the mechanical and it still reads the same

 

my mech autometer gauge in the water pump usually sits around 180degrees at long as i'm moving. thats with one fan, small griffen rad, and 160 degree thermo.

 

Mine in 95 degree weather...cruising it stays at about 180 without my A/C on...if I turn A/C on it will go to about 190. Coolest weather I have had it in so far is about 80 and without ac it sits down in the 173-177 range...I think its bouncing up and down on the thermo opening. With A/C it cruises at about 180. Mine had a hard time idling smooth at the 80 degree mark...but then again in South Florida this time of year 80 is cool.

 

I'm hearing that most people are getting same temps as me...at least in warm weather. Again, mine will be aroudn 175 or often less. But with teh cool weather, I can't even get heat out of the heater.

I'd interest in hearing if anyone is experiencing that problem. No heat in cold weather is not fun. And doesn't seem normal to me.

 

I'm not sure what you mean when you ask does it go into C unless you mean Closed Loop. I'm running a SDOL tune on mine.

Yes I do have the steam line hooked up. When I come to an idle it will heat up to 190 on the gauge and then my fans come on @ 195.

Bill

 

I agree with you analogy of the coolant entering one side being cooler and exiting being warmer. That is what I figured the difference was on mine all along.

Bill

 

What I mean is not only does mine not reach 175 on teh guage, but the needle goes down to just barely above the C (cold) on the guage. Again, that is when I am driving 55mph in less than 50 degree weather. If I am idling, it will come on up to warmer readings.

My heater is putting out barely warm air.

 

Have you checked to make sure that there is no blockage in the heater core? If it's blocked, one hoses will be hot & the other much cooler.

My head temps run from 155F-180F depending on ambient temps & the heater works even @ 155F. IMO & relatively speaking, the only time that low coolant temps are a bad thing is when the coolant temps are low enough to keep the oil temps from reaching 212 F + or -10 F. As long as your oil temps reach this optimum running temperature, the engine is not running cool; in terms of engine operating clearances.

Sounds like there's a blocked heater core or a blockage in one of the lines running to the core.

 

My bet is that the heater core is airbound. I have never really paid attention to the heater core location in a tri-five, but I am betting that it is high on the firewall like my El Camino.

Ever since I put my El Camino together my heater seemed to work intermittently, one day it was fine and for the next few it barely threw heat..... unless the fan was on the lowest setting. Eventually I pulled the heater hoses off one time when it wasn`t throwing heat.........and found that there was virtually no flow from the engine. There was nothing plugged or restricted, it just seems like these motors don`t have a lot of coolant flow through the heater core.

I fixed the problem by installing a flush T right as the coolant exits the heater core. Now if it seems like the heater is too cold I just open the cap on the flush T and it vents the air out and the coolant starts flowing through the heater core again. I have had to do that probably 4-5 times in the last year since I figured out why the heat only worked sometimes. Eventually I want to run a small bleed line from the T to the steam line/radiator so that the air will automatically purge from the heater core.

 

That's interesting. Although I'm skeptical that is my problem, because my heater inlets are not hight on the firewall, and more to the point, it puts out great heat if my engine temp is approaching 175. But, when the engine temp is at or just above the Cold mark on the guage it is not hot. That is normal in any car.

My problems seems to be that the engine just runs too cool.

Another thing that seems odd: both heater hoses from the pump on this engine are right beside each other, at teh suction area of the pump, and the thermostat is right there too. So two things: if both lines are at the suction part of the pump, how can water push or pull through the heater core? I guess it does, as if engine is warm, I have heat. The other thing that seems more pertinent is that with those lines right by the thermostat, if the thermostat is passing cooler water, that cooler water is being moved right throughthe heater core. But, if the thermostat is a 195 thermostat, then why is it moving cold water.

NOne of it makes senses to me. My original thought that the thermostat was bad made sense, but having tested it, I find it works just like it should.

I'm stumped.

I am putting the steam vent on tonight. I'll see if that makes a difference, altough the weather has warmed up, so I may not find out for a bit.

I suppose another option is to put something over the front of the radiator so not so much cold air moves through it. I'd rather the engine work like it should for cooling.

 

The two heater hoses are not on the same cold side (suction) of the pump. Internal to the pump is a hot and cold side, so the smaller 5/8" hose is the hot side and the 3/4" hose is the cold side. When the thermostat is closed, it blocks the cold side from the radiator. Internal to the pump, the hot side will bleed through the four holes in the thermostat and also push the hot water to the heater. The heater control valve should be a bypass type so that it continues to circulate hot water back to the water pump. I asked this question once before and appparently few realize the heater valve, when closed, continues to circulate hot water not throught he heater core but rather back to the pump.

Regarding your cool running motor, have you tried changing the thermostat to a different temperature rating to see if you can verify a change? Is the thermostat the correct application? The symptom does seem to indicate it's not closing fully. Also, is you heater control valve closing correctly? Did you purge air from the heater core?

Most modern systems are very efficient and need correct temperature control (thermostat). Without one that functions correctly (in the open position), it will over-cool the motor. I remember once the thermostat in my Ford Explorer broke (open), and the temperature gauge barely lifted off of 'C' even when climbing a grade in 80 degree weather.

Andy1

 

Thanks so much for your time here...

Very interesting. I'll have to study that pump close with the tstat out. With that off, it looks like both have same access. It didn't look to me like that thermostat installed would in any way impeded wither heater hose line. I guess I didn't study that enough...in fact for sure, I didn't evaluate "What if the tstat was there?"


I've read somethign about that before. Now, of course, I have it hooked up the old way, as would be in a 1956 Chevy. So, I wonder if this may be causing problems. by the old way, I mean, large hose to heater cord, small hose to other side of heater core. No bypass type valve. Not sure what I'd need to rig up for htat...and of course, that'll be a pain, as at the moment I have fabricated stainless braided hoses hooked up. So, I may be heading down that path before long.


No I have not tried a different thermostat. I have tested it by putting it in water, boiling it, using a temp gun, and watching to see when it obviously opened. Of course, I suppose it is quite possible that it is barely opened earlier and I couldn't tell.

I think the thermostat is the correct app. It is one that came with a billet housing specifically for this year/Model of LS1 (i.e. 2004 Corvette apparently would be different from a Camaro LS1), purchased from S&P. that being said, maybe I should change it while I have it open anyway. I had called S&P and Mark thought my having teh steam vent plugged was my problem. I'm not convinced of that. but I'll have that corrected tonight.

I did not purge air form teh heater core, but that wouldn't cause the engine itself to run cool would it? Again, the heater works great when the engine warms up.

Yep, that sure makes sense. My testing made me feel that the Tstat is OK. But again, maybe I should go ahead and change it.

Thanks again for your detailed input.

 

The comment in just earlier about the heater valve should be a bypass type got me to thinking some more. I called Mark at S&P again, and discussed. I had not told him on the first call about the heater blowing cold too.

Now, he thinks that water is flowing through the heater constantly and that is probably my problem. (Note: the aftermarket Vintage Air A/C-heating system heater valve is a cable operated mechanical valve in the hose. I'm sure some water gets past it).

Anyway, he said I should put some kind of restriction in the hose so that not so much water gets through. For example, put something that restricts the 5/8 hose to 3/8 hole.

Hmmm...maybe I'll try that.

But, I wonder how the bypass thing not being there would play into this.