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Overheating after rad trans cooler bypass

68 Sport Satellite said:
What's best way to trim thermoplastic? Vise and a hack saw?
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I'd say skip the vise, just find a reasonably low table or bench and gently hold it in place with your foot while you use a hacksaw. Remember that all inside corners where the cuts intersect have to be rounded to avoid cracking from engine vibration. Either do this with a soldering iron after you cut it, or predrill the inside corners with a sharp drill bit, then cut to the hole.
 
After reading all the issues and suggested remedies associated with your overheating I have to come to the conclusion that your engine is making more BTU's of heat than your cooling system can dissipate. All suggestions by the posters are true and correct and remain possible causes of the overheating problem. You rarely hear of people suspecting fans mounted backwards, thermostats installed upside down or lower rad hoses collapsing. But at the end of the day, if you can't get rid of the excess engine heat you'd have to suspect the problem is really an undersized radiator. Measure the coolant discharge temp and then the return temp at the radiator, and if the differential is too close you'll hit the upper limits of your cooling system and never cool the engine properly. Use a laser thermal gun on the upper and lower tanks with the engine at about 2000 rpm's while parked and blocked in your garage. Mount an electric box fan in front of the grill to simulate air traveling across the front of the grill at highway speed. You should be able to maintain a differential of a least 25 degrees across the entire rpm range. Read this article for more info. You may find that a new, larger surfaced rad is required to deal with engine heat.

http://www.enginebasics.com/Engine Basics Root Folder/Engine Cooling Pg2.html
 
I've got a shroud that mounts up! FINALLY. I had to do a bit of cutting, but not too bad. Used my Multimaster vibration cutter that I had bought when I did my bathroom addition a few years ago. Used a semi-circular brass blade with heavy grit impregnation on the blade to cut, then used a 120-grit sandpaper attachment to smooth things out. Worked awesome! Better than I expected. I cut the lower rad cutout a little too big, but oh well, it's down low.

Question - even though this shroud has offset, in the correct and most fan space friendly orientation I only have 1/2"-5/8" clearance between the fan tip and shroud edge. Is this enough? I have the Schumacker poly motor mounts along with the Schumacker rigid Turnbuckle torque strap, so the motor is fairly solid in there. Fan is an original late 60's - early 70's steel 7-blade 18" diameter fixed fan.

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It turned out the plastic shroud that fit my rad mounting was from an early 70's A-body. I only knew it might work because the guy on ebay posted the hole spacing dimensions.
 
Water pump pulley vs. crank pulley size also is a factor. Your radiator might not be big enough for that new engine/power. Then add ac on top of that and you'll have find out real quick that you need a bigger radiator. But for now, lets focus on the pulley size's......4 groove crank pulley should measure measure 7.750, water pump pulley I'm not sure, but use one for an ac car.

Last thought, pull the water pump off the housing and see if you have a 6 or 8 blade pump and also check to see if it still connected to the shaft. Seen it before!
 
Found a shroud that fits! Finally. Confirmed fan facing direction was correct all along. Fan pulls a bit harder than before, but still overheating to 225
image.jpgimage.jpg

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Really pleased about finding the shroud and that it fits perfect after my trimming. I needed it anyway
 
Did temp mapping today with IR gun. Also used meat thermometer in rad coolant with cap off for a few minutes. From all I can tell, although my motor is running hotter, it may be ok and I think my temp gauge is reading high by about 20 degrees

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Rad coolant measured with meat thermometer was 170 near neck after 2 minutes idle and gauge read approximately 190. After 10 minute warm up gauge read much higher than the Ir gun readings of 185 at the water pump housing, t-stat housing, and next to engine block gauge

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image.jpg

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The square box is facing the radiator. H is heads, I is intake, T is t-stat housing or engine temp probe, h2o is water pump housing

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Nothing over 185 at idle so if at cruise I am reading gauge at 225 that means I am about 205 in reality. Had car idling off and on for twenty min at a time all day today while tuning and no radiator steam or spewing. Must be fine yeah?
 
Can you get an el cheapo water temp gauge and see what it reads?
 
Have you properly 'burped' the cooling system? Jack up the front end and let the car get to temp with the rad cap off?

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68 Sport Satellite said:
Found a shroud that fits! Finally. Confirmed fan facing direction was correct all along. Fan pulls a bit harder than before, but still overheating to 225
View attachment 314274View attachment 314275

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Really pleased about finding the shroud and that it fits perfect after my trimming. I needed it anyway
Click to expand...

Looks great!
 
I have not burped the system that way...do I need to? How high do I raise the car - 3 or 4 inches? What you say makes sense, but I had not had any issues before. Do you think my IR temp map shown above indicates air pockets by a few of the cold spots near the top right, or is that normal?

Bigal75 said:
Have you properly 'burped' the cooling system? Jack up the front end and let the car get to temp with the rad cap off?

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Looks great!
Click to expand...
 
3 or 4 inches is perfect. Then you let it idle until all the air pockets come out...if there are some.

I think you would prefer your car to stay below 200 so it's worth a try. Have you gone on the hwy then tried the temp gun?
 
I'm glad you figured out the issue. I've been following the thread to see what turned out to be the problem. I figured that at the temp you were showing that you should have been pushing out water but you never said that was an issue. With a closed system I've always just filled the radiator to within 2 inches from the top then fill overflow bottle. Bring up to operating temp then let it sit overnight. The system will level itself out.
 
OK, so it seems after all of this, the gauge in my rebuilt non-ralley cluster is reading incorrectly! I'm glad that's all it is. I bought a cheap mechanical temp gauge and today I installed it in the same exact location as the old temp probe that was wired to the dash, which is one of the ports in the top of the aluminum water pump housing, right next to the hot side heater hose port. After motor warm up for 10 minutes I'm getting a steady 180F temp at idle, then I put it in gear and drove a half mile and had a steady 190F. Can't beat that! I'm going to probably leave this gauge in there until after Spring Fling. Before the shop worked on my car, the cluster gauge mirrored these numbers. I'm not sure how or why a bit of under-hood work installing a Carter mechanical pump with new line to the carb and a new trans cooler could have made this happen, even if the probe wire was bumped around. If that wire got pinched or dinged, could this explain the super high reading?
 
I would think it's a resistance issue, but without a previous baseline it would be hard to know. maybe the rebuilder can give you insight and resistance specs. usually under 5 ohms for wiring I think. I might be wrong
 
Sorry, it took me so long to read this thread, but I would have pointed to the Converter.. I do think your temps changed and that the car was running cooler with the 2800 stall converter. Which is CRAZY!! I think your converter is to tight. You fixed the extra heat for the trans, but not the issue of you engine having to make extra power to overcome the converter.

I am glad you found the resolution to one problem, but I think you may still have a problem.
 
iT WAS THE ORIGINAL SENSOR GOING BAD?, DONE DEAL GLAD YOU GOT IT FIXED. SORRY FOR THE CAPS
 
This is almost certainly a grounding issue. My bet is your gauge cluster and the sender are not sharing a good ground. When we broke in this motor, we did not rely on the gauge. Only an IR thermal gun was used. Plus, I think the thermostat got changed from 160 to 180, so temps should have risen about 20F anyway in that change.

It's easy enough for someone to knock a ground loose or for a poorly tightened ground to come loose. Check the ground, and I bet you'll find your issue.
 
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