LT1 people

BigWheelinBubba

BigWheelinBubba

Club Member
Just bought a cool sleeper. 1991 GMC Safari with a 1994 Z28 LT1/4L60E. It has a new aluminum radiator but the guy said he could never keep the temps steady. It's either freezing cold or he said it gets hot in summer traffic.

It has an aftermarket electric fan on it, but it only covers about 70% of the radiator and has no shroud.

I want to remedy this before it becomes a problem. Well, actually it is now not having much heat lol. But anyway..

I already bled the system out today and it had very little air in it. It helped the temps climb up a little but still not hot enough.

I'm going to swap out the thermostat.. he said it has a failsafe in it now that stays open just a tiny bit. I think with the temps being so cold it never gets a chance to warm up completely. It runs at between 120-160 right now.. i'd like to see it stay around 180 give or take.

Anything I might be missing?
 
LT1coolantflow_zpsdcfb9cad.jpg

If it has that small line on the top of the radiator make sure its not going back to the waterpump. Just went thru this on my truck. New rad was drilled wrong and was pushing hot water thru the vent to the back of the tstat
 
1BADAIR said:
LT1coolantflow_zpsdcfb9cad.jpg

If it has that small line on the top of the radiator make sure its not going back to the waterpump. Just went thru this on my truck. New rad was drilled wrong and was pushing hot water thru the vent to the back of the tstat
Click to expand...

Ive had a dozen lt1 b cars and put an LT1 in a Porsche 944. That cooling mech is a little odd.

Rad hoses are right.

First let me know if you have a rad with a rad cap or not.
If no rad cap, plumb it like a Caprice.
Heater hoses come off the right side. Heater is on top, heater return is on bottom. Heater return is tee'd with the surge tank (pressurized coolant bottle) steam lines come off the back of the head and go to the vent port on top of the surge tank. You can decide if you want to send heat through the throttle body.

There is no overflow tank required in addition to the surge tank.

If there is a rad cap, there needs to be a vent port under the cap, that goes to an over flow bottle (not pressurized) and a vent port below it I the rad end tank. Hook this port to the steam lines from the back of the head. The heater lines are the same but do not have a tee to a surve tank. The reservoir is not pressurized.

Hth

Sent from my SCH-I545 using Tapatalk
 
beertestr said:
Ive had a dozen lt1 b cars and put an LT1 in a Porsche 944. That cooling mech is a little odd.

Rad hoses are right.

First let me know if you have a rad with a rad cap or not.
If no rad cap, plumb it like a Caprice.
Heater hoses come off the right side. Heater is on top, heater return is on bottom. Heater return is tee'd with the surge tank (pressurized coolant bottle) steam lines come off the back of the head and go to the vent port on top of the surge tank. You can decide if you want to send heat through the throttle body.

There is no overflow tank required in addition to the surge tank.

If there is a rad cap, there needs to be a vent port under the cap, that goes to an over flow bottle (not pressurized) and a vent port below it I the rad end tank. Hook this port to the steam lines from the back of the head. The heater lines are the same but do not have a tee to a surve tank. The reservoir is not pressurized.

Hth

Sent from my SCH-I545 using Tapatalk
Click to expand...
Thanks for the input gentlemen. :cool:

Mike it has a rad cap and an overflow bottle. It has the heater hoses on the passenger side of the radiator. I'm going to go out in the garage later and take a better look at it and see what's up.
 
If everything checks out externally, the next place I'd look is the thermostat. Make sure it's an LT1 stat, not a conventional SBC stat. But, the erratic temperature swings sound more like an unpressurized system.

tstat.jpg
 
Everything checks out Mike.. only thing left is the thermostat which from what the guy told me is a "cold" stat, so i'm thinking it has a 160* in it. Might not have to mess with it though now that its' warming up outside :)
 
Could be a funky or wrong stat. Keep me posted, I'm happy to help out. I'm trying to think what happens if the bypass circuit is not closed when the stat opens.
 
Sounds cool, is it AWD?? Pics?? I just changed t-stat that was newer b/c the fail safe worked and stuck open. Replaced it with a Normal one and heat is back.
 
Subbing because it looks as though I'm going to be dropping the same year LT1 into my old Buick, assuming it's not thrashed anyway.
 
I took the easy way out and put a piece of cardboard between the rad. and condenser for now. It has heat and runs around 185 at the most. It's been too cold to mess with it with no heat in the garage and my arthritis acting up.

I'll post some pics once it warms up enough to get it cleaned up.

I took it on a little ride to Almont the other day and it did surprisingly well on fuel, using a little over 1/8 tank there and back.. taking M53 there and a few back roads on the way back ;)
 
Here's a pic from the 2nd owner that I just happened upon via a friend. Found out the van has head work (alum), cam, and a tune as well as a built 4L60E and the rear end was just redone last summer.

safariwithoutstripe_zps0de442ca.jpg
 
I've been throwing around the idea of some old school Cragar SS's like a 15x7 up front with a 15x8 or 10 in the back.. just hard to find a cheap set that's 5x5 bolt pattern.
 
Thats sweet...i have been looking for two used 15x12 rim with a 5x5 bc and no luck...i'm going to have to buy new.......I do have 4 Chevy rally rims with a 5x5 bc and there a 15x8 but they need blasted and painted that i might sell soon..
 
BigWheelinBubba said:
I've been throwing around the idea of some old school Cragar SS's like a 15x7 up front with a 15x8 or 10 in the back.. just hard to find a cheap set that's 5x5 bolt pattern.
Click to expand...

Find some uniluggers. They go 4.5-5" trouble is the BS is usually 3.5" on the 15x10s so you end up with Mullet Camaro look. I abandoned the idea after a lengthy search. Find a modern wheel with the S/S or Torq Thrust looking spoke.
 
BIGCOWL-IMP said:
Thats sweet...i have been looking for two used 15x12 rim with a 5x5 bc and no luck...i'm going to have to buy new.......I do have 4 Chevy rally rims with a 5x5 bc and there a 15x8 but they need blasted and painted that i might sell soon..
Click to expand...

Stock car wheels. I am running them for my slicks on the 79. 15x10 in my case, but you can get 4-6" BS for whatever tuck you need
 
TooSlo86 said:
Subbing because it looks as though I'm going to be dropping the same year LT1 into my old Buick, assuming it's not thrashed anyway.
Click to expand...
The biggest issue you're going to have is disabling the VATS but otherwise it's a pretty straight forward swap.

Beertestr seems to have a lot of insight and willing to help if needed :thumbsup:
 
BigWheelinBubba said:
The biggest issue you're going to have is disabling the VATS but otherwise it's a pretty straight forward swap.

Beertestr seems to have a lot of insight and willing to help if needed :thumbsup:
Click to expand...

If you use a 94-95 contoller (service number ends with 8051 IIRC), I can do basic tuning mods like turning off VATS and speedo cal with Tunercat.
 
BigWheelinBubba said:
The biggest issue you're going to have is disabling the VATS but otherwise it's a pretty straight forward swap.

Beertestr seems to have a lot of insight and willing to help if needed :thumbsup:
Click to expand...

Did 94's have VATS enabled on the B-body LT1's? I know when I dropped a 96 Vortec drivetrain into my '72 C-10 I was worried about that but in that case they didn't implement it until 97.
 
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