Overheating after rad trans cooler bypass

Or to small for THAT engines needs

But maybe being under load causes more heat

CoronetDarter said:

The higher stall converter definitely generates more heat, so all things being equal installing a low stall converter should not be the problem. And as you say, if after the car warms up at idle and stays below 200 then it's not an airflow issue.

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I was thinking that too so I drained the rad and refilled with 75% coolant 25% water plus some purple ice from royal purple and a new pre tested stant 180 t-stat. No change. By the way what is liquid capacity of a stock 22" rad? My aluminum exact fit stock dim griffin with 2 row x 1.25" tubes only took a hair over 2 gal (2 prestone bottles worth of 75/25 mix). I thought that seemed a little low.

cdr said:

sounds like the radiator is plugged up.

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Your block holds around 4-5 gals I thought If you only put 2 in the rad then you are just mixing a small percentage of the mix you made with what is already in the block. I know it's a pain but maybe drain the block and rad then refill it all with your new mix? Other than stall speed the only other thing I could possibly think of like another mentioned is timing, I made a mistake once with it and got 230° at cruising speeds was terrible, went and readjusted everything and added a A/F ratio gauge to help and got it dialed in.



I was thinking that too so I drained the rad and refilled with 75% coolant 25% water plus some purple ice from royal purple and a new pre tested stant 180 t-stat. No change. By the way what is liquid capacity of a stock 22" rad? My aluminum exact fit stock dim griffin with 2 row x 1.25" tubes only took a hair over 2 gal (2 prestone bottles worth of 75/25 mix). I thought that seemed a little low.[/QUOTE]

Not trying to hijack your thread, but what kind of lights do you have in your cluster???They are pretty sharp!

You shouldn't go more than 50/50 mix. It's not helping with the heat exchange. It sounds like you don't have enough rad for the combo. It's odd ...I don't remember if you have a shroud or not. If you don't then install one to see.

Bigal75 said:

You shouldn't go more than 50/50 mix.

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x2 - in fact, it's hurting things, as water is a better conductor of heat than the glycol. The fluid serves simply as a corrosion inhibitor and to depress the freezing point so as to prevent frozen / cracked engine blocks, so it's best to keep it to the prescribed ratios.

The viscosity of glycol is higher than water so takes more to pump it and it draws less heat
With that info use only enough antifreeze to protect engine for expected cold (freezing point )

No shroud. I know I need one. I've tried 3 and they didn't fit. I finally think I found one that at least calls out the correct mounting dimensions. It's from a '72 A-body. It should be here next week and we'll see. If not, then I'll have to get a universal aluminum shroud kit and try it.

I thought water was better at cooling than the glycol coolant, so in theory 75% water SHOULD cool better shouldn't it?

Although I am completely in favor of a shroud, will a shroud alone reduce the temp from 225F back down to 200F??

Bigal75 said:

You shouldn't go more than 50/50 mix. It's not helping with the heat exchange. It sounds like you don't have enough rad for the combo. It's odd ...I don't remember if you have a shroud or not. If you don't then install one to see.

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straight water cools best and since i'm in california, I went with 75% water. If that's not going to cool better, I don't understand why.

Anyway, there was no change in engine temp from 50/50 to 75/25 (75% water)

HT413 said:

x2 - in fact, it's hurting things, as water is a better conductor of heat than the glycol. The fluid serves simply as a corrosion inhibitor and to depress the freezing point so as to prevent frozen / cracked engine blocks, so it's best to keep it to the prescribed ratios.

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Shroud, shroud ,shroud

75% water / 25% coolant makes a lot more sense, especially in San Jose's weather. Look up at post #42, you had it reversed - 75% coolant 25% water lol

Yes it can. Another thing, is there a gap around the radiator and the rad support? If there's too much of a gap air can be going around instead of through the radiator. Also have you tried to run without a thermostat? 75/25 water/coolant sounds much better.

Hey on one of the other threads someone posted a photo of a home made aluminum radiator air shield like this one but I can't find that thread. I am wondering about making one. Did these come stock on some Mopars? I see plastic ones listed for 67 but not 68.



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I received a new repop shroud that yesterday that I found with correct mounting hole dims. I will attempt install today and see if fan alignment is correct.

In the event that the shroud still does not help enough, I have 2 other things I am looking into before I resort to adding electric puller fans:

Larger water pump pulley to change fan speed
22-lb rad cap to replace my new 16-lb cap

Please provide experience and feedback for these 2 items
Thanks!

One thing I forgot about until just now reading your feed back request, lower radiator hose spring, It might not sound like much but the increase of pressure with a 22 lb cap caught my eye. I had a pressure build up due to collapsed lower hose and the huge sucking power of the water pump. The stainless steel spring prevents that. best $5 investment.

I asked for hoses with springs when I bought my new hoses last year and they said they don't make them like that anymore due to stiffer hose wall. Not sure if that is true. I don't believe I have any collapsing hoses, but Thankyou for that idea.

bigmanjbmopar said:

One thing I forgot about until just now reading your feed back request, lower radiator hose spring, It might not sound like much but the increase of pressure with a 22 lb cap caught my eye. I had a pressure build up due to collapsed lower hose and the huge sucking power of the water pump. The stainless steel spring prevents that. best $5 investment.

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I have an update! I really thought when the light bulb went off this morning in my head that I would have a success story, but NOOOO! Still struggling with this, but at least I corrected one more issue.

So I got to reading about vacuum advance and the ported vs manifold vacuum connection debate. Learned more than I did last year. Sooooo... This morning I got to looking at my quick fuel 735 carb and low and behold that vacuum hose was hooked up to the PVC valve port on the side of the carb. I reconnected it to manifold vacuum (closest to carb mounting flange at front of carb) , ran the car till warm and no change. Darn it. See pics below.

I really feel this is a tuning issue! So even though the engine temp shot to 225 again after a warm up and only driving around the block and back, what is puzzling is that as soon as I put the car in park and let it idle, within literally 20 seconds I can watch the temp gauge drop dramatically without the car moving. So no engine load and low airflow. The shroud may help, but there is something else going on here!

See before photo of 225 after driving and the one after it reading around 195-300 is 20 seconds after parking at idle.

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by the way, I am and always have been, running the 16-lb rad cap.
I only asked about difference if I went with a 22-lb cap because I've read that can help, but I wanted to ask you guys first.

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I also checked timing on the car after switching the vacuum advance connection from the carb pcv vacuum line to manifold vacuum.

Initial timing = 22
Total at 3000 = 40
both measured with vac advance hose removed and plugged

Checked vac adv can with 3mm allen wrench and it's 16 turns lock to lock. Currently set for full advance at full clockwise and still no engine cooldown. If I dial it back CCW at all to reduce engine ping under load, it would make things heat up even more, correct?

Trying to rule out all possibilities: is my fan mounted facing the correct direction? My find are curved TOWARDS the rad.

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Fins not find

Ok... if it cools down at idle but heats up at road speed (and your engine is good, timing is ok and jetting is close) then it's an airflow issue.

Really? Then why won't it cool down at freeway speeds??

I removed the fan and the part number stamping was facing the radiator. Was this correct?

Bigal75 said:

Ok... if it cools down at idle but heats up at road speed (and your engine is good, timing is ok and jetting is close) then it's an airflow issue.

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With the fan in this mounting it pulled a piece of paper hard to the outer rad face in front of the grill.
If fan is backwards will it pull at all??

Sorry I wrote it down backwards. Airflow issue at idle and rad is not large enough for Hwy. It could be the water pump, blockage in the rad. I've been there. I ended up needing a radiator. I had the same issue.

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Just trying to help.

Ok I'm measured my water pump pulley and it's 6.5" diameter. Is that the one for A/C cars?

I mocked up shroud and I think it will work but first I need to trim for lower rad hose and upper arc where it gets wider at rad support.
What's best way to trim thermoplastic? Vise and a hack saw?

hmm

http://www.forbbodiesonly.com/mopar...r-bypass&p=910401308&viewfull=1#post910401308