89 r3500 building heat

[tinse4]

OK I am new to posting here, but am at a loss. I have an 89 Chevy r3500. I know its past the age, but for all purpose the same truck. Specs: 454 tbi th400 trans 411 gears. The issue I am running into is it keeps building heat in the engine. It has dual electric fans that seem to be operating right. I have replaced the entire front of the engine. I started with the fact I could not time the truck. Turns out the harmonic balance slipped. While there replaced the timing set, water pump with a heavy duty model. The radiator was rebuilt, and rodded out. The tech that did it said it was a custom job and wondered where I got it. It was in it when I bought it. He said it would keep a semi cool. New stat, and hoses installed. New alternator custom 140 amp , power steering pump due to leaks, and hydro boost. I have spent a lot of time and money getting it running right. With the ac on it will over heat, all the way red if i let it. With the ac off it runs about 190 for about 30 mins, then starts to creep. Down the freeway today it hit about 225 in 100 degree weather. This was 65 mph at 3200 rpm. So I am left to think restriction in the exhaust that is cause the heat creep, or the ac which is all new is doing it. I know this is long, but any thoughts would be great.

 

[Stepside Billy]

A clogged cat maybe? Don't know for sure if that would cause the engine to heat up like that but free flowing exhaust helps.

 

[foamypirate]

I'd do a pressure test on the cooling system. Could be a head gasket.

 

[yevgenievich]

Diuble check the water pump impeller direction

 

[tinse4]

So Sunday I pulled the stat. I figure that way I can rule out the stat. I live in Tucson so it was a chilly 95 with humidity from monsoons. Drove the truck around town with the ac off to see what the engine is really doing. The temp never even hit 210 while in traffic at almost 100 degrees. So I am thinking I may have gotten a bad stat. I still want to get it on the freeway and run it with the rpms up for a stretch to see what its going to do. I know I have a cracked manifold, and an exhaust leak in the pipe. I may just do a new exhaust anyway. I plan to not only use this as me work truck, but a weekend hauler also. Will post more when I know more. Thanks for the responses

 

[tinse4]

Ok so after some more playing. I removed the cat. I dont need tags for another year so am not worried. It helped power, but not the heat. Last night I drove to my moms house to pick my girls up. Its an hr drive one way half freeway, and half in town. Here is what I found. With the ac on the truck heats up. When I run the blower on Hi I can watch the volt gauge drop then the temp climbs fast. With the blower on low or med it would run about 230-240. With the ac off the truck runs right at 210. Now I am in Tucson and it was easy 94 yesterday. I have a custom built 140 amp alt. Im running electric fans for the radiator. So my thought is that the blower may be worn, and drawing to much current. That in turn is dropping the signal to my ecm and either leaning my fuel or some other signal issue causing it to over heat. Thoughts....

 

[Georgeb]

Or your belts are slipping and you aren't fully driving the water pump and alternator.....

 

[highdesertrange]

or your gauge is off. highdesertranger

 

[tinse4]

So some more test driving. On the freeway for 20 mins with the ac off it runs right at 210. Run with the ac on it goes to 230 -240. With he egr unhooked the truck runs like a different truck, more power, quicker response. Also the heating on the freeway slows. Isn't the egr supposed to cool the cylinder temp? So I'm now wondering if I dont have an issue there. I can make the truck stumble at idle while moving the egr, so I know it good. I put a hand vacuum pump and added vacuum. When I release pressure it closes, and truck evens out. So the egr works, but how do i test the egr vac solenoid?

 

[Joe383]

Check the color of your plugs too. Could be running lean. Don't focus too much on the timing on your damper. I use a vacuum gage for timing. I tried to set my current motor at 10* timing and it would not run proper. I have it at 16* now. Your motor might need more or less timing than what the book recommends. Check all plugs too. I had a motor about 2 years ago that I just bought that ran smooth and it was only firing on 7 cylinders. I told a few other people it was on 7 and they did not believe me tell I pulled the #7 plug and it was a black ball of carbon for a plug. I had to drive the car 100 miles and it stayed 230* the entire trip. It ran like it had all 8 cylinders. 3K is high RPM to cruse at in a 454. You need an overdrive.

 

[Scottycutlass]

454 with AC where known to over heat. My 88 has a separate electric fan from the factor that runs with the AC and the fan on the engine that moves air all the time. It makes since the temp increases when the AC is on, the refrigerant condenser is in front of the radiator, when the AC is on the condenser is letting off heat for the refrigerant cycle which is being forced across the radiator buy the air moving in from the grill. As anti freeze gets old is starts to plug up the heater core first and then the radiator since these ports are the smallest for the water to go through. Have you noticed any heating issues? That would lead to a dirty coolant system. Also if the head gasket was leaking would would notice coolant in the oil at the bottom of the pan when you change the oil, or oil in the top of your radiator after the truck sites for a while.

 

[tinse4]

Ok so I think I have the building heat fixed. I removed the electric fan assembly that P.O installed and went back to fan clutch. I figure go back to stock and work back. It was like a whole new truck. I don't know what the amp draw of the fans was, but even with my 140 amp alt they were killing my engine systems. So now down the freeway in high 70's truck never hit 210. My assumption is the electric fans and shroud were blocking the air through the radiator at highway speed. Down side is in traffic it gets hot. I can not find a fan shroud for my radiator. My core is 34x19. So next remove the clutch fan and install new 3000cfm 16" electric fan center of rad without a shroud. My hope is this will make enough air movement at idle, and allow enough air flow at speed. I will post when the results are in.

Next question. Anyone have any info about emissions after removing A.I.R injection. My manifolds leak, cat is removed so I know I have some exhaust work to do before August. I am thinking new long tubes, cat, flowmaster to redo the exhaust. I just don't want to fail emissions.

 

[yevgenievich]

Fan needs a shroud, otherwise as you found out it will not pull enough air. Junk yard search to find something that fits close enough. On emissions, depends what they test. Just going with a cat might work good enough

 

[tinse4]

I have a internet search for a shroud out now. So for nothing. As far as inspections I don't have an under the hood inspection due to year and weight. I do have a under side visual and exhaust gas test. I am more worried about the output without the A.I.R. My understanding is it pumps air into the exhaust stream to dilute the emissions. So then my logic is that if removed the O2 sensor will lean out the fuel ratio to bring it in spec. Might help mileage, but I don't know how far the computer can adjust. I know a rich truck will fail the tail pipe test.

 

[highdesertrange]

if you have an O2 sensor, that means you have a computer. oh wait is this the '73. a '73 should not have an O2 sensor. did I miss something? what engine you got? carb or FI. highdesertranger