Getting up to 250 seems too high .. but if you were climbing and getting on it for 20 mins combined with a slightly inadequate cooling system that makes sense. What are the dimensions of your radiator?

Anything majorly blocking your airflow like a winch, 900 KC lights etc?

As for spiking to 210, these LS like to live at 210 ... LQ4, LQ9, etc etc.

 

Do you have a heater in the rig or the bypass hose or the heater fittings plugged in the water pump? Seems I have ready problems with plugging the heater ports but mine is like that and never gets over 210.

 

I do have a vintage air setup in the truck with the evap in front of the radiator. The radiator is the largest I could fit, like 19 x 31 or something.

Yesterday I jacked up the front of the truck about a foot, took the cap off, cranked the heater wide open started it and ran it for about 15 minutes. I kept squeezing the hoses and felt the thermostat open.

I did get some air bubbles out I believe, I haven't ever really burped it with the heater on so that could have been where they were hiding.

I went and drove it up some climbs by my house and it only got to around 210 and then settled back down, but puked fluid again. I will check it and see if the radiator is lower again

 

Sounds like you need a new radiator cap. It shouldn't be puking at 210.

 

How is the steam vent hooked up ?

 

I called griffin and asked about the cap and whether I should bump up to an 18 and they didn't want me too.

Maybe I will try a new cap

The steam vent plumbs directly into the radiator below the return hose.

I ran the truck with the front elevated and like I said I have lost a lot of fluid again. The level is down about three to four inches below filler neck. Gonna try filling it up via the upper hose

 

Anyone know what the stock pressure of a lq9 rad cap is?

 

What are you running for fan ?

 

If I were having heating problems on a LSx series, I would get a vacuum bleeder/refiller and use it to make sure all air is out.

 

Anyone know what the stock pressure of a lq9 rad cap is?

 

All the Gen3 trucks I've seen have a surge tank, and use a 15psi cap.

 

Looks like it may have been a bad cap. I replaced the cap with another 16 lb cap and went and got the engine up into operating temp and no puke. The spring in the stock cap did seem quite a bit weaker than the new cap.

Will see how it does with reg use. I put a clear bottle in place of the overflow I had to be able to visualize how much fluid I was losing and will monitor.

 

steam vent must be hooked up

i drilled it into my water pump

 

Yea the steam vent is fine. My radiator has a connection for it.

I believe it was the cap. Must have been marked wrong as I haven't lost any coolant recently lol

 

nice when its an easy fix like that. Keep us informed on the long term result.

 

the only frustration with all this is Griffin. I popped for an expensive $900 radiator from them when I did the swap and the first one sprung a leak. They wouldn't warranty it unless I sent it back to them on my dime and they would take a look at it.

Not really that convenient or easy. So I said F it and bought another griffin without the fans and shroud and swapped over that stuff onto the new radiator.

I have an overflow tank but have dealt with the leaking and seeping for so long I was convinced it was another faulty Griffin radiator but I just didn't want to deal with it so I just kept adding coolant.

Well it started to drive me crazy and the overheating last weekend was the final straw. To find that the radiator cap was "potentially" mislabeled or faulty is relieving but also frustrating as it is yet another griffin prod to let me down.

The upside is that I towed my trailer up my local pass this weekend and the temp didn't get above 204 and no puked fluid.

The downside is that for the $1200 I have spent on radiators with them I would have hoped it would have been hassle free.

Oh well, live and learn. It is working for now, will see how it does on the trail next time out.

 

I normally run 16 pound cap on my LS engines.
When I had my LQ9, the temp stayed at 210 no matter what I was doing. (Cross flow, double pass 24x19 rad + Taurus fan)

 

Yeah ls engines are alot easier to cool than old sbc, i run the stock sbc radiator when i swap those trucks and the 67-72 if the truck shows up with a good usable radiator. Hell even 2000-2007 silverado radiator hoses fit with a little trimming.

I know it sounds like you fixed your problem but just curious why you arent running the stock clutch fan? Yeah it takes a little bit of power to turn it when it isnt locked up but not enough to worry about in a wheeling rig and when it does lock up you sure as hell cant beat it for moving air which is what i would want for a slow speed wheeling rig.

 

Yeah ls engines are alot easier to cool than old sbc, i run the stock sbc radiator when i swap those trucks and the 67-72 if the truck shows up with a good usable radiator. Hell even 2000-2007 silverado radiator hoses fit with a little trimming.



I know it sounds like you fixed your problem but just curious why you arent running the stock clutch fan? Yeah it takes a little bit of power to turn it when it isnt locked up but not enough to worry about in a wheeling rig and when it does lock up you sure as hell cant beat it for moving air which is what i would want for a slow speed wheeling rig.

Great question. Honestly wasn't thinking of overheating issues so went with electric but hindsight being 20/20.

Also the engine I went with didn't come with clutch so I just ordered fans.

 

I have spent a lot of time in the Billsvista cooling bible. So much tech. I am leaning towards a surge tank. I presume I would either get a two way radiator cap or just move my pressure cap to the surge tank? Stupid question but what would I cap the radiator with? Do they make non pressurized radiator caps?

 

Dont waste your time. A regular radiator setup with a overflow bottle will work absolutely fine, all of the ls swaps ive done i have never used a pressurized surge tank and never had a problem. Can you run a 99 and older silverado radiator cap or similar on your radiator that will let the fluid come and go as it heats/cools?

 

I've done it both ways. Put a higher pressure cap on the radiator. 20 psi or so and plug the overflow port then put your 15-16 psi cap on the surge tank. Or cut the filler neck off the radiator and weld a cap on it.

 

I like the idea of a two way cap with overflow for simplicity but the surge is cool for filling and extra capacity.

With surge I would just use a cap with no pressure rating so the surge was just balancing?

 

I like the looks of this, but don't like the price tag. lol

 

I run the Howe Surge tank. Works well.

https://www.summitracing.com/parts/hre-3424