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Discussion Starter · #1 ·
I've got a 1990 360 bored .030 over. Compression is 9.5:1. Cam is a Crower 50 state C.A.R.B. legal, .465 / 465 roller. Radiator is brand new, heavy duty, for a '90 360 RC w/A/C, heater core is new. Factory shroud is in place, fan sits just inside of shroud. All leak path areas around the radiator and condensor have been sealed to ensure that the fan is pulling max air through the condensor, trans cooler and radiator.

All accessories are conventional v-belt driven. No oil in the coolant, no coolant in the oil. Factory air cleaner with a K&N element.

Coolant is a perfect mix of 50 / 50 Prestone and distilled water. Heater core is brand new. Fan clutch is a brand new Hayden heavy duty unit. I'm running a 360 TBI on an adapter plate on an Edelbrock Alum. intake. Ignition is factory computer, (1990), MSD Cap, rotor and wires, NGK plugs. Coil is an new Accel mounted on the firewall.

Trans is a A518 built to Cummins specs with a Trans Go shift kit running a TCI (+ 2) quart capacity trans pan and a 27k gvw 10 pass cooler in series with the radiator.

Torque convertor is a custorm ATI all torrington rollerized "specialty" designed to lockup tight at 2200 rpm (which it does), which helps the truck leave, but is also suitable for towing. Max trans temp when towing my 6,000 lb. boat and trailer is no more than 205 deg. F, verified by a Pro Comp mechanical gauge. Gearing is 4.56:1, running 37's.

On a 90 deg. day, the motor will get so hot, (after you run it hard), the coil, (Mounted on the fire wall), gets too hot to touch and the motor will actually bust up and pop back through the TB from the heat.) Oil pressure is fine. 20-22 psi at idle and 65 psi at 2400 in overdrive, with Valvoline 10w40. The temp. gauge runs on the last "Whole" hash mark before you get to "Hot."

I've had everywhere from the factory service manual specified 195 deg to (2) different 180 deg. stats in it and it still runs hot. The only thing I haven't changed or replaced is the radiator cap itself. The water pump is the Mopar performance standard duty replacement. I even pulled 2 quarts of coolant out of the rad to make room for (2) bottles of Water Wetter, with little to no improvement.

What is causing this motor to run so hot? Since installing it, I've only logged a little over 650 miles on it. Have changed the oil twice. Everything looks great. This motor screams and makes tons of torque, just like it was designed to. I only run 93-94 octane fuel in it at 8.5 deg BTDC.

What is keeping this motor operating so hot? Can I expect it to loosen up and break in and cool down considerably after putting a few thousand miles on it? Don't know what else to look at. Like I have said, everything is new.

I've set the idle speed calibration per the manual and the initial timing at 8.5 degs. advanced, (down from 10). I'm begining to wonder if the coolant temp. sensor has gone haywire and is dialing in some rediculous amount of "Total" timing while running down the road??? I'm stumped.

Thoughts / suggestions would be appreciated..Hurry.

Thanks,
Dave
 
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I don't know for sure just how much headroom you'd have with the stock TBI computer, but that's the first place I'd be looking....a run-lean condition that's causing the excess heat. An example of the limits these particular units imposed, is the use of 360 TBI/PCM on even the stock 318, and pretty much a must-have for coverage with any decent mods.
 

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Discussion Starter · #3 ·
Trying to understand what you're getting at.... Are you speaking of the "Piston down in the bore" dimension? '1990 used the SBEC, (Single board Engine Controller). Are you suggesting that I may need a "PCM" as in a "JET" computer mod, interface or upgrade? To richen the mixture delivered by the stock TBI?
Thanks,
Dave

gen1dak said:
I don't know for sure just how much headroom you'd have with the stock TBI computer, but that's the first place I'd be looking....a run-lean condition that's causing the excess heat. An example of the limits these particular units imposed, is the use of 360 TBI/PCM on even the stock 318, and pretty much a must-have for coverage with any decent mods.
 

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if its not running lean as suggested here and in the last post about this / l,m still sticking with core shift / in the 30 years l,ve been rebuilding motors l,ve seen it happen about 5 or 8 times / basically the water cores in the block are not were there suppose to be centered around the cylinders / there offset to one side and that makes the cylinders thinner than normal / exspecially after its bored is when it shows its ugly head / the thinner cylinders generate more heat into the coolant and the motor runs hotter
 
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Sorry. What I meant by "headroom" was the amount of built-in coverage the PCM has for mods, which isn't much when it's a 360 PCM on a 360. These particular PCM's are not adaptive, so if you go beyond what they can cover, you'll run lean. Even if the PCM's could adapt, you then would run into injector limitations at some point. With the mods you listed, I' immediately thought of this issue, though I'm not sure just how much you can get away with. Just as an example, the same-era 318 with 360 PCM/TBI and a low restriction muffler picked up an easy 15hp. Mopar even marketed this as an upgrade in the early 90's. So, the 360 would probably have benefitted similarly if it'd had a bigger brother to borrow from (meaning even stock, with just better exhaust, the added air/fuel was being used...and needed). It may be that you're getting enough fuel (injector capacity is good enough), but not enough air (too-small throttle body for mods), which results in a rich condition, and can also cause an overheat (and if this is the case, may explain why you're not rattling like a woodpecker in a paint can). Then, the O2 sensor picks up the fuel, leans out, then enrichens, back-and-forth....You really need some tailpipe analysis. I agree with Bogger that it could easily be core shift. For that matter, it could be something else. It's just that inadequate fuel control/supply capability is the first thing I think of with your type of situation. There aren't many mods for the stock PCM, but I think there's a Jet chip, and there's always a custom programmer. Aftermarkey stuff from Holley would be the easiest way to keep TBI, but open up performance.
 

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Discussion Starter · #6 ·
This motor was specifically built to work with the stock 360 "PCM" or SBEC. Believe it or not, I think I figured out what is causing the problem. When I replaced the fan clutch, (Finished up in the dark), I think I installed the fan backwards...So much for us rocket scientests!!

Does anybody have a picture of what the proper fan installation, (direction), the fan looks like when it's installed correctly? From what I can see in the extremely lousy picture in my FSM, looks like the closest edge of the fan blade to the motor is on the driver's side and the farthest edge away from the motor is on the passenger side of the blade viewed from the front of the truck. I think one good picture would tell the whole story...Would really appreciate a picture if anyone has one.

Thanks,
Dave ???
 

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Have you tried verifying coolant temp with a thermometer in the radiator? I use a $2 meat thermometer for this, just to make sure my electrical (mechanical autometer gauge was bad out of the box :mad: ) temp gauge was reading correctly. Obviously not 100% accurate, but will tell you if your sending unit has gone south.

You may want to tap an O2 sensor into your exhaust and hook it up to an air/fuel ratio gauge to see if you are running lean.

-SM
 

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run an external mechanical gage,on the block somewhere,the compare the two to find out if it is reading accurate,i'v had a simular prob on my big block,i added a external cooling fan to the outside of the radiator that pull the air through helping the clutch fan to adjust to the changing temps,i'v also seen that a water pump malfuntion and actually let the turban spin freely on the shaft which slows down the flow of water through the block.if you have access to a computer,snap-on or mentor,check the readings to the p.c.m,and keep a cloce eye on you coolant temp sensor,if it seems to spike at a rapid rate you might want to change it over,a false reading from a coolant temp sensor,would tell the engine to burn leaner causing the temp tp climb..hope this helps a little..
 

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Discussion Starter · #9 ·
Curlymc,
Great minds think alike. UPS just delivered a Pro Comp mechanical temp. gauge today. Stopped on the way home and picked up a new coolant temp. sensor also. If you saw my last post, I'd really like to see hwat the stock clutch fan installation looks like. Pictures anybody?

Thanx!! ;D

curlymc said:
run an external mechanical gage,on the block somewhere,the compare the two to find out if it is reading accurate,i'v had a simular prob on my big block,i added a external cooling fan to the outside of the radiator that pull the air through helping the clutch fan to adjust to the changing temps,i'v also seen that a water pump malfuntion and actually let the turban spin freely on the shaft which slows down the flow of water through the block.if you have access to a computer,snap-on or mentor,check the readings to the p.c.m,and keep a cloce eye on you coolant temp sensor,if it seems to spike at a rapid rate you might want to change it over,a false reading from a coolant temp sensor,would tell the engine to burn leaner causing the temp tp climb..hope this helps a little..
 

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Well, if it is a stock fan, it say engine side on it. But, it shouild have the pass side closer than the drivers side, as it spins clockwise as you look thru the rad, and the 'curved' part of the blade should trail the flat part as it spins clockwise.
 

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the fan is easy / if it blows air towards the motor its on right / if it blows out the grill its wrong
 

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My vicous fan clutch was out. It showed no symptoms of being out, either making a loud noise or freewheeling. When it heated up I spun the fan and it had the same resistance as it did when it was cold. (Thanks shedevil) I swapped it out and it was fine. Could you have been sold a bad one?
 

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Discussion Starter · #13 ·
PROBLEM SOLVED !!! Bad coolant Temperature Sensor, (TPS), was creating a lean condition. Replaced the bad one with a $17 Borg Warner sensor tonight and the temp. runs right around the thermostat rating of 180-185 degrees. Thanks to all of you guys that offered feedback and suggestions. I appreciate it! It wasn't until I decided to look at the codes that I decided to look at the TPS. It's amazing how much better / easier it starts and runs now.

Thanks again.
Dave
 

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Discussion Starter · #14 ·
How much difference would the Mopar Performance "6" fin water pump make as opposed to the "8" fin heavy / severe duty pump make, when towing? I'm thinking either change the pump to the 8 fin pump or a smaller pulley to drive the pump/fan faster?? Thoughts/ideas? The thermostat I have in the new 360 is the same 180 deg. that worked so well in the original 318 I towed with and it worked fine, no overheat problems.
Dave
 

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I installed an 8 fin pump after I had my engine rebuilt. Got it from Summit racing and the guy there sold me a hi-flow therostat and housing to go along with it. The housing and stat didn't fit and after some researching I found out they don't make a small size thermostat that is a hi-flow for a 360. If you have an aftermarket intake manifold it might be able to accomodate larger hi-flow thermostat which you're really supposed to run with the 8 fin.
My truck has been runnin good with a 180* (non-hi-flow) thermostat, one can of water wetter and 8 fin water pump in it. I haven't broken it in yet so I haven't let it come close to overheating. I guess the 8 fin is working well.
If you find a "stock" size hi-flow thermostat let me know.
 

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Discussion Starter · #16 ·
I'm sure I've got a lean condition causing the heat build up after dumping the codes this morning before I went to work.

52, "Rich F/A Condition or Excessive leaning . O2 sensor signal input indicates rich fuel/air ratio condition during engine operation. Also, "Adaptive fuel valve leaned excessively due to a sustained rich condition.

What is the the "Adaptive Fuel Valve" tha the FSM refers to??? Fuel pressure regulator?

Also got code 24, TPS voltage too low or too high meaning the throttle position sensor inputs are either above or below the min / max acceptable voltage levels.

The Coolant Temperature sensor is new. The coolant temperature gauge sender, (single wire pass side of intake), looks like the post that the wire goes on is bent. (May have been damaged when the AC comp. was installed. Also had to splice, (With a crimp butt connector), a new end onto the old wire. Old connector gave up due to corrosion. New connector is a marginal fit. Also used teflon tape to install and prevent possible leaks.

O2 sensor has probably 55-60K miles on it. MAP sensor is original at 146k miles on it. Injectors are new Mopar 360 units. TBI temp sensor has approx. 50k miles on it. TPS has 55-60k miles on it. Fuel press reg. is original, 146k on it. Thermostat is the same Robert shaw high flow one that ran 180 deg.in my 318. Idle speed motor has 40k on it. Clutch fan is new. Radiator and water pump is new.

Something is causing the motor to run lean once it reaches the mid point of the temp. gauge.

Any thoughts ideas now? I'm desperate to cool this motor down. Don't want to tow with it getting as hot as the gauge says it is. When you throw the hood, its HOT.
HELP....
Dave
 

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Discussion Starter · #18 ·
I've got a good spare MAP sensor. I'll change that first to see if that makes a diffference. The FSM diagramming that shows how all the sensors work together to make the system work, all except the temp gauge send unit. As I read on though, it sounds like this sender does send info. to the computer that is a second input relative to temperature that may also affect TB lean out. I've ordered a new one from Mopar. Should have it tomorrow. I'll replace it and see if it makes a difference, in addition to remaking the butt splice connection to the wire that snaps on the sender with a solder joint and some shrink tube. If this fails to make a favorable difference, I'll start looking at the thermostat and then the water pump efficiency, along with replacing the O2 sensor. Again, this motor was built around acceptable operation with the factory TB and stock SBEC. I'll replace one component at a time till I find the bad actor.
Dave

gen1dak said:
Regardless, I'd replace the O2 and MAP sensors.
 

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Discussion Starter · #19 ·
The MAP sensor, temp gauge sender and TB temp sensor along with the new radiator cap seem to have made a big difference. Temp. going down the road, (Not towing) is ok, but still looks like under load it's going to get hotter than we all like. The new radiator I installed is a new style Modine High Efficiency model........I'm going to check, but I swear I think this radiator is a 2 core "Turbulator" type which just isn't providing the kind of cooling I need for this motor. Brand new, wrong one... Hope my buddy at the parts store will take it back under warranty. Found one at National Radiator, (3) core just like the factory one, lifetime gurantee for $144.00 They're located in Philadelphia and offer free shipping and guranteed 1 day delivery... Other than this, this thing is running like a scalded rabbit now.
Dave
 

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I'd sure like to hear what happens with your adventure! I swapped a remanufactured 360 in for the orig 318 in my 1990 RC and have been battling heat ever since. I also replaced the radiator and hoses and 160 deg thermostat. I suspect fuel starvation issues using the 318 computer and I am replacing the stock unit with a Megasquirt controller and an electronic distributor.

Any additional feedback on your experience would be appreciated.

Good Luck!
Bruce
 
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