'89 R3500 Crew Cab 2wd to 4wd conversion & beyond

[miniwally]

I have the CTS reading on the Holley and the Autometer gauge. The senders for both are located at the front of the intake before the thermostat. Technically the Autometer was giving me a higher reading once the motor got over 200F. So when I'm saying I would stop at 220F to cool off that was what the EFI told me and the Autometer was usually reading closer to 230F.

The Sniper EFI does not monitor knock. I did look and it was holding 40 degrees advanced during this time. I have not delved in to the tuning possibilities yet. I just downloaded the software and stopped there. So right now it just runs on the base tuning as well as the learned tuning the onboard software does for the first however many miles of driving.


I was curious what you were running for a fan on the 8.1L. I don't know if you remember the climb up 285 from 470, but it's pretty tough. Too bad you don't still live here so we could do a direct comparison. Obviously I was being passed by newer trucks pulling bigger campers as I sat on the side of the road cooling off, so it's not an issue for the newer trucks. The camper weighs about 4000lbs, so I try to remind myself between truck and camper and family and gear I'm probably hauling nearly 13,000lbs. Maybe I'm expecting too much from a factory 80's truck 454. I also had to pull Nick's truck up Kenosha Pass and it was heating up pretty quick doing that but it's a relatively short climb.


I think that will be the next step. I'm deciding between 2 options. Factory 6.2L mechanical fan (uses same fan clutch as 454) and shroud. I found I can get a 6.2L shroud from Classic Industries. My only concern is trail cooling. I was just reading @the_blaze thread and he's having idle cooling issues with the same mechanical fan and shroud.

The other option is 2 bigger electric fans on a shroud that covers the entire 19"x34" core. I have (2) 16" 2-speed Volvo fans I could try that with. Or I could go bigger and get (2) Derale 2-speed 17" diameter fans and max out the coverage. I'm kinda leaning this direction because I know it will still work on the trail.

If your AFR is 14:1 at higher loads/full throttle you're too lean. It needs to be down around 13:1 and even as low as 12.5:1 at full throttle. Add gas and it will probably cool down.

All the advice about making sure the cooling stack is sealed etc. are good too. An oil cooler isn't going to hurt but I also don't think you'll see it fix anything either. It might knock the time it takes to heat up back a bit, or the rate it cools off but I don't see it fixing the overheating. That said I would put one on.

 

[ZooMad75]

I know this, Larry's 8.1 in either his k10 or suburban are running the same big block/6.2 radiator 8.1 fan and hd clutch and a stock shroud to match. Both trucks can idle through 100 degree ambient temps with the ac on and not run past 200 on the gauge.

Just food for thought.

 

[Kay86K5]

I was curious what you were running for a fan on the 8.1L. I don't know if you remember the climb up 285 from 470, but it's pretty tough. Too bad you don't still live here so we could do a direct comparison. Obviously I was being passed by newer trucks pulling bigger campers as I sat on the side of the road cooling off, so it's not an issue for the newer trucks. The camper weighs about 4000lbs, so I try to remind myself between truck and camper and family and gear I'm probably hauling nearly 13,000lbs. Maybe I'm expecting too much from a factory 80's truck 454. I also had to pull Nick's truck up Kenosha Pass and it was heating up pretty quick doing that but it's a relatively short climb.


I think that will be the next step. I'm deciding between 2 options. Factory 6.2L mechanical fan (uses same fan clutch as 454) and shroud. I found I can get a 6.2L shroud from Classic Industries. My only concern is trail cooling. I was just reading @the_blaze thread and he's having idle cooling issues with the same mechanical fan and shroud.

The other option is 2 bigger electric fans on a shroud that covers the entire 19"x34" core. I have (2) 16" 2-speed Volvo fans I could try that with. Or I could go bigger and get (2) Derale 2-speed 17" diameter fans and max out the coverage. I'm kinda leaning this direction because I know it will still work on the trail.

I remember that hill...I towed my blazer up that hill in my 1996 K2500 when we went wheeling that time up on Kenosha Pass (Wade should remember, he was following me in his semi going slow, haha). That's a good size hill no matter which way you look at it.

The rule of thumb I've always heard is if you want to tow with your truck, mechanical fan is your best bet to keep it as cool as possible. E-fans are more for off-road as they will see lots of idle time so it's a good way to force more volume of air through the radiator on command (once again, rule of thumb, not black/white rules here). So in your case where you are using the truck for both, and if it were me, I would get the mechanical fan setup properly first (with the idea of a good mechanical fan/clutch and a good shroud that covers the whole radiator) and make sure the motor is cooling good for road/tow use. Then take it off-road and if you still see your temps climb a little bit with lots of off-road idle time, then figure out an additional secondary e-fan to aid in those situations.

 

[Kay86K5]

I know this, Larry's 8.1 in either his k10 or suburban are running the same big block/6.2 radiator 8.1 fan and hd clutch and a stock shroud to match. Both trucks can idle through 100 degree ambient temps with the ac on and not run past 200 on the gauge.

Just food for thought.

I have the exact same cooling setup on my 8.1...it finally hit over 100*F here yesterday, and I took my CCLB for a drive (no A/C yet...I won't do that again until I get A/C working again, haha) and my temps stayed below 190* the whole time, both highway driving and stop/go city lights too.

 

[ZooMad75]

Larry's k10 with the camper loaded for the desert trip tipped the scales at 8,000+ pound so it's no light weight either. The camper gives all the aerodynamics of a barn door too.

 

[Tnsejed]

Like was stated before though and Miniwally re-iterated, if you don't have any commanded enrichment under load its going to run hot. That combined with no knock sensors is a recipe for a visit from the other side. Lol.

With what you stated before that you changed nothing other than the 4l80e, magnum, and the injection system, then the truck started to run hot, i'd be double checking the Holley settings and make sure they are correct.

 

[mrk5]

Like was stated before though and Miniwally re-iterated, if you don't have any commanded enrichment under load its going to run hot. That combined with no knock sensors is a recipe for a visit from the other side. Lol.

With what you stated before that you changed nothing other than the 4l80e, magnum, and the injection system, then the truck started to run hot, i'd be double checking the Holley settings and make sure they are correct.

The injection system was on there a year before I did the 4l80e/Magnum swap and I didn't have overheating problems. Ran around Moab on the trail in 105F without overheating issues (unless you count melting holes in the ARB plastic lines). However I also didn't tow the camper because I didn't figure the 700r4 would like to be stuck between the 454 pulling on side and the 4000lbs camper dragging on the other end.

If I go out and pull the camper from here to Denver with it being 95F, the engine temps will run right around 195. As soon as I stop at a light it will cool down under 190F if I sit long enough. It's just the hill climbs. The trick I will need to figure out is how the enrich the EFI for the hill climb scenario. Nice thing with the 4l80e is I can just switch tables for the towing, not sure if it's that easy in the EFI. After all the Sniper is just the baseline, low cost EFI system.

 

[mrk5]

Larry's k10 with the camper loaded for the desert trip tipped the scales at 8,000+ pound so it's no light weight either. The camper gives all the aerodynamics of a barn door too.

Scary thing is the crew cab weighs that with just me and my normal gear in it.

 

[ZooMad75]

Scary thing is the crew cab weighs that with just me and my normal gear in it.

The only time the K10 hits the street is if he's going to the desert or mountains. So it's loaded all the time.

 

[Tnsejed]

The injection system was on there a year before I did the 4l80e/Magnum swap and I didn't have overheating problems. Ran around Moab on the trail in 105F without overheating issues (unless you count melting holes in the ARB plastic lines). However I also didn't tow the camper because I didn't figure the 700r4 would like to be stuck between the 454 pulling on side and the 4000lbs camper dragging on the other end.

If I go out and pull the camper from here to Denver with it being 95F, the engine temps will run right around 195. As soon as I stop at a light it will cool down under 190F if I sit long enough. It's just the hill climbs. The trick I will need to figure out is how the enrich the EFI for the hill climb scenario. Nice thing with the 4l80e is I can just switch tables for the towing, not sure if it's that easy in the EFI. After all the Sniper is just the baseline, low cost EFI system.

Oh interesting. So just the 4l80 and magnum did it then. I would be surprised if holley did not have a power enrichment setup already in their system. The idea is to just check that its on. Other than that lots of good ideas to work with for now and whittle it down. Cooling issues suck.

 

[sweetk30]

4l80-e is a BIG trans and the t-conv on it is about half its weight . then add in the mix of driving threw the aux range box there is more drag .

 

[mrk5]

Figured out the blown air line. It was the plastic line from the ARB manifold to the gauge I have in the cab.



Interesting thing is it's quite far from the exhaust. Must speak to how susceptible the plastic line is to the heat.



I didn't take the crew cab on the trail run Saturday because I found this under the truck:



Actually I ignored it until we got the gas station. Then I saw it dripping and leaving a couple of quarter sized spots just in the little time we were stopped to fill a tank. That's when I decided to turn back.

The puddles above were left from sitting a couple days after the 4 days of wheeling and pulling the camper. I checked the back of the intake, distributor, and the valve covers and they are all dry. It has to be coming from the rear main. I think the front seal might be leaking too based on the amount of oil all over things. I feel like there must be something going on that's is linked between this and my overheating issue. Is there something that could be going on with the oil system that would promote leaking?

I have good oil pressure, although I did notice a few times the oil pressure dipped when the RPM hit 3500. The sender for the oil pressure is located at a port at the front of the block just above the oil pan. I feel like the the high volume/high pressure pump is f-ing things up.

In my poking around, I also noticed the oil pan has a dent in the bottom. Maybe this is causing trouble for the oil pickup. Might explain the dip in pressure I saw, but don't see how it would relate to the oil leaking out. So then I'm wondering if I messed up the rear main seal install and that's why it's leaking.

Looks like I'm going to pulling an oil pan. Gonna swap the oil pump and see about the dent in the pan. Might was well replace the rear main while I'm at it.

Good grief, it's like the thing is going to hell in a hand basket on me.

 

[skunked]

What's the crankcase pressure like and are you vented enough?

 

[mrk5]

That's what @Bent77 and I have talked about. I put a new PCV valve in a month or so ago; an AC Delco unit. I also changed out the billet aluminum breather for an open element K&N breather. PVC passenger valve cover, breather on the driver side. I haven't experienced anything odd like the dipstick being pushed out. We did a compression test on the motor last year and all cylinders were good. Did not do a leak down. I'm not burning any oil. At least not out the exhaust, just on it.

 

[mrk5]

The other thing that occurred to me this morning is all of this started after I changed the filter. Meaning filter brand - the oil is the same (not the same-same, I changed it and put the same brand back in). I was running a K&N filter which are touted for their high flow but now I'm using an Amsoil filter. Not saying the filter is causing the problem, just contributing to what I think might be an excessive oil pressure issue.

 

[Bent77]

Maybe the filter is leaking

 

[mrk5]

I didn't look closely to see if the filter had a bunch of oil on it. I mean based on everything else I'm sure it does, but whether or not it's leaking from itself.

It occurs to me what I really need to do is crawl under the truck and and look around with the motor running. I'm 90% certain it only leaks while running. The puddles don't continue to get larger after sitting a day or 2.

 

[imiceman44]

You said the oil pressure dips when you revved it up to 3500 rpm?
That's my problem with high volume or high flow oil pumps.
If you don't have a bigger oil pan for more volume you end up starving it on high rpm.

 

[mrk5]

I've got a big 7qt pan. The only reason I got the HV/HP pump is because it was suggested for use with the pan. I was afraid maybe a standard pump could draw the oil up from a deeper sump or something. I kinda wonder if the dip in pressure has to do with the dent in the pan; like it's interfering with the pickup.

 

[sweetk30]

I've got a big 7qt pan. The only reason I got the HV/HP pump is because it was suggested for use with the pan. I was afraid maybe a standard pump could draw the oil up from a deeper sump or something. I kinda wonder if the dip in pressure has to do with the dent in the pan; like it's interfering with the pickup.

scott @4X4HIGH who use to build engines in his old shop told me sbc and bbc do NOT need anymore than std flow and psi pumps for almost all builds cause it sucks a pan dry and also can over oil in places it dosnt need and take longer for oil to get back to the pan .