lsxRanger94

He's talking about the black piece of rubber under the core support that almost every vehicle has. It creates a high pressure area under the vehicle in front of the radiator and low pressure behind at highway speed and forces air through the radiator. some people knock theirs off by hitting parking blocks...LOL

slogo

I don't know if this is worth saying or not, but we had a pickup in the shop doing something
real similar, turned out to be water pump impeller was all rusted and part of the fins were
just not there, on the outside the pump looked good. Good luck.

slogo

Sorry, I went back and read more I see you already replaced pump.

Jeepthing

Interested in more info on the heater core bypass valve. Based on the thermostat getting its temp from the in hose what exactly did you do? I have read about bypassing completely with a u bend hose or plugging entirely but not about the valve...

Willing to give anything a shot at this point...

Punisher8738

iTrader: (1)

I purchased a 3/4" ball valve from Lowes near the hot water plumbing. Simply cut the hose supplying the heater core and installed it.

Thought the pic showed the ball valve but it hidden under the intake tube. My apologies.

Punisher8738

iTrader: (1)

Sorry duplicate

Jeepthing

I may add the heater core valve just to have it, thanks for the info. Still not 100% sure how it would help based on how the thermostat gets its temp input from the "IN" heater core line though. I assume at the base level it allows the coolant to pass through the radiator more often since you have removed some of the system??

I like the intake, did you locate the filter in the cowl area or take it all the way inside the passenger compartment? If you have more pics would love to see some.

Thanks again to all who have offered insight, apparently this is a common issue....

Punisher8738

iTrader: (1)

The way it was explained to me is that when the thermostat opens to allow the cooled coolant from the radiator to flow into the engine, it also allows some of the hot coolant from the heater core circuit to flow with it. The ball valve basically shuts off the heater core so there isn't a loop of hot coolant sitting there. Coolant only flows from the radiator to the block and so on.

Yeah I have river raider expedition snorkel on mine. I removed the original cap and use a k&n filter that has a threaded post on the top. The lampshade style cover protects the element.

Originally I had a Ripp supercharger on my 4.0 and the filter/cap came with their snorkel adapter.

Curtis who was with SNL Performance fabricated the intake tube to keep the snorkel functional. Initially we tried the filter where the coupler is inside the hood and then the one on the snorkel. No loss at all and the IAT's were lower as well. So. Basically have a functional cold air/snorkel.

Jeepthing

Thanks for the explanation, that makes perfect sense now. The ability to drop temp with the valve is certainly nice but does seem to me to be a bit of a Band-Aid fix. Not knocking your set-up at all, I know some factory vehicles use that method, just on the LS I doubt it should be required for us to get to normal temps.

Thanks for the intake info, looks like a pretty cool set-up. I have considered doing something similar but no time currently.

Stu Cool

iTrader: (13)

Just a quick question, are you using the factory thermostat housing and thermostat? There is one aftermarket housing on the market that uses the old style SBC thermostat and that will cause problems because it does not have the extra disc to control part of the coolant circuit. It allows hot coolant right back into the motor instead of forcing it into the radiator. BTDT

Jeepthing

I have the stock thermostsat and housing so the thermostat has the rear disc for proper function of the water pump bypass circuit.

Jeepthing

I was able to get the hood vents installed and relocated the intake over the past couple days. I also removed the light bar I had on the front near the winch.

Just got back from a test drive and saw a max temp of 225 going uphill under load maintaining 70 mph. This would be RPM of 2,500-3,000. It is possible temp would go higher with more sustained hills/load. Under normal driving at 65 temp stays about 212. With the heater on full blast temp was down 10 degrees under all conditions. Highest IAT I saw was 145, down from 170. IAT on highway was about 120.

Problem is definitely load based as normal highway seems ok to me. I want to say that I have seen various other factory LS engines have the #2 fan turn on at 230+ degrees. What max temp is acceptable under the above conditions?

Avarookie

iTrader: (8)

I had a very similar issue years ago with sbc. I won't go in to all the paths I took to fix my cooling issue. Short story is with the t-stat at high speeds it would get hot, just the opposite with out it. Pull it and see if it follows suite. If so, try stewart t-stat, it has three extra holes drilled in the ring of it, to allow some coolant to move at all times (might work, if not cheap to try for your application). If not, I ended up making restriction plates until I got the happy medium. Basically they are pieces or metal cut to the diameter of the t-stat, with different size holes.

Jeepthing

Thanks for the post! Just checked out Stewart Components and I didn't see any thermostats for the LS system (no rear disc for bypass function) but I could be wrong. Could be worth a call on Monday to discuss with them.

With temps ok on the highway except for under load it leads me back to coolant flow and not air flow.

I think some additional changes need to be made no matter what to feel comfortable. Removing the thermostat and shroud seem to be next logical steps. Finding a higher CFM fan is also an option. I may also add some vents in the inner fenders as a to of air escapes from the edges.

Thanks again to all, appreciate the time to give your experience and input!

Avarookie

iTrader: (8)

Check in to Robert Shaw t-stat as well. To be clear, this was in a 80's sbc, I am not sure either have a LS style t-stat or not.

What type of fan are you running? If running a mechanical fan, is it set in the shroud correctly? Rule of thumb is fan blade width is covered about half way by the shroud. (i.e. if looking down at the fan and shroud the fan blade should be about half way covered front to back). This picture is only to show what I am talking about, nothing more, see the depth? (I should mention, this pic is a random one from the internet, not mine)


How close is the fan to the radiator? If it is too close, say with in a inch for example, it cannot cool the whole radiator, only the area just in front of the fan. The use of a shroud and the fan set correctly is very important. I learned this years ago from building hot rods. In my Impala SS, after putting a ATI D-1SC, I was getting very hot at Woodward, I ended up making my own shroud with two electric fans. I know it's hard to believe, but I dropped about *80. It always sat at 170*-185* even on the hottest days in humid weather. As you can see, it doesn't take much to make, and it cools the whole radiator area. I could not go with a different fan system, the inter-cooler tube ran right down the middle of the radiator face. So I had to split the area accordingly. If you are going electric, make sure to seal the whole diameter of the frame to the shroud so you are only pulling through the fan area, and not from around the frame of the fan frame. This will get you 100% draw. Even through the radiator, a/c condenser, intercooler you could feel the air draw past your legs with shorts on.
Get the idea? You can see in the picture below, the fans are actually sucking in the smoke from all around and in to the radiator area.

Pop N Wood

iTrader: (1)

More load = more heat to cool = runs hotter

This is true whether your problem is coolant flow, air flow or too small of a radiator.

In some respects increasing any one of the three will make up for the other two.

lsxRanger94

Just a thought, but have you looked at your A/F ratio and timing while this is happening?

lsxRanger94

I had seen no one had suggested raising the back of the hood to test airflow through the engine compartment. It can be done with a few washers and longer hood bolts. It will save cutting any holes and it works to test. If it comes down more, then your hood vents you installed may not be big enough.

lsxRanger94

For a baseline. My 2008 express ext 4.8 runs 210 all day long no matter what the outside temp and 220 with the a/c on and fully loaded with equipment.

Jeepthing

Jeep has been dyno'd after the swap and tuned with HP Tuners. After the first dyno session we saw the jeep was running a little lean so hence the tuning to get things in check. I will keep an eye on it next drive though just to be sure.

I have removed the hood and driven on the highway but temps still higher than I would like. I might add some vents to the inner fenders as lots of heat can be felt at the edges.