Trust but Verify - Vintage cooling system upgrade lessons learned

[EyezOpen]

Originally Posted by BJohnsonsv

I love the evolution of the commentary. On behalf of the OP (me), I'd dare posit that the original post is about cooling system upgrades/overhauls on properly operating, vintage, carbureted engines. While I appreciate that it diverged to the fine-grained points of where excess heat might be generated in the combustion process of fuel injection and even in aircraft, it feels like its trending away from upgrades to the systems that remove the heat in normally operating carbureted automotive engines.

Don't get me wrong. It is vitally important that all engine operations must be checked and dialed so that there isn't a hot-running condition. Both identifying and resolving the source of excess heat and the removal of excess heat are important topics.

Your RV rebuild is the most complete and well-founded work I've yet to see and it was a thourgh job. My question as to why the elec fans now have been answered...this fuel/timing question and answers took on a life of it own in a way but a lot of good information has been displayed. I find myself in a position now as to what to post..I see you have a background in emission tech so I'm quite sure you understand the ramifications of responding how to eliminate quite a bit of heat..but only if one's emission system is no longer functional nor repairable..The whole system would need to be eliminated and that might cause some ire..Yet left in a state of nonfunctionality it is a super polluter..

[NeilV]

Originally Posted by GypsyR

Wait, what was this thread about?

Mitigating excess engine heat which is about more than putting in a bigger radiator or higher volume water pump. You need to get to the root cause or source of the excess heat which often is not really just the cooling system.

You also have to be cautious about having too high a coolant flow as coolant flowing too fast through the system can diminish thermal transfer in either the engines water jacket or radiator or both. A engine water jacket that's dirty isn't going to have a good thermal transfer for example regardless of how big a radiator you install nor will it correct a plugged up, worn or mal-adjusted carb running lean under load or a distributor where the advance system is not working correctly.

All these systems have to work together to mitigate excess engine heat.

In the Computer Controlled Engines most are accustomed to today this is all orchestrated by the computer, servos and sensors however on the old legacy engines each of these systems works independently and has to be kept in balance by the mechanic who maintains the vehicle.

[GypsyR]

Hmmm, yeah. Sometimes tongue in cheek humor doesn't quite come across on the internet.

Plus you never know who you might be talking to. Here's me at the place I've been foreman of for about fifteen years. I might possibly know a thing or two about "vintage" cooling.

[udid]

The following will illustrate and show the results of LOP/ROP and it's relation to CHTs * EGTs.

https://www.youtube.com/watch?v=h3bATVXMHQg

[EyezOpen]

Originally Posted by udidwht

The following will illustrate and show the results of LOP/ROP and it's relation to CHTs * EGTs.

As always combustion topics are quite interesting, with that being said RV engines have multiple handicaps when it comes to heat build. I think it is important to understand a very basic occurrence in an 80's CARBED engine's RV engines....smogged RV engines. This thing called timing...it fires the plug that fires the gas charge in the cylinder. Now these specific engines RV smog engines Fire that charge...late...very late. So late up to 50% of the gas charge per cylinder goes out the exhaust header to be reignited once again to fully burn off any smog...Yes i said that correctly about 60/50% of the charge is burned off for power combustion the exhaust valve opens...the fuel is then reignited burning off any smog..By being burned off in you exhasut manifold it beomes a thermo heat reactor..that is the source of 85% of heat problems including vapor lock...Modern fuel boils at 160 degrees..exhaust headers hit 1600 degrees and the block absorbs much of that.

[EyezOpen]

Originally Posted by EyezOpen

As always combustion topics are quite interesting, with that being said RV engines have multiple handicaps when it comes to heat build. I think it is important to understand a very basic occurrence in an 80's CARBED engine's RV engines....smogged RV engines. This thing called timing...it fires the plug that fires the gas charge in the cylinder. Now these specific engines RV smog engines Fire that charge...late...very late. So late up to 50% of the gas charge per cylinder goes out the exhaust header to be reignited once again to fully burn off any smog...Yes i said that correctly about 60/50% of the charge is burned off for power combustion the exhaust valve opens...the fuel is then reignited burning off any smog..By being burned off in your exhaust manifold it becomes a Thermo heat reactor.. which is the source of 85% of heat problems including vapor lock...Modern fuel boils at 160 degrees..exhaust headers hit 1600 degrees and the block absorbs much of that.

Finally found an illustration of this unburned charge going out to the exhaust manifold. It is actually a flame thrower of sorts.. Note the "RED" in the exhaust cycle..that is your emission control system of 40 yrs ago at work...

Below is a fairly well articulate article on the subject...and right below is an article on how to cool an engine that needs help..

Understanding How a Smog System Works - Clean Living

[bigbe66]

1972 250 revcon
i solved the cooling by using a new radiator from a large gmc late 90s big blk truck - and aftermarket trans cooler - all working fine.
i have rebuilt the 455 - check all of the rebuild info from Joe Mondello - all of his articles will help - especially the oil plugs that have a hole to oil distributor - most rebuilder miis this.
But now that my init is running fine i want to order the 19.5 wheels AWS - but i want to confirm the bask spacing and measurements
Thx Much Bigbe66

[doc50]

I'm the guy with 71-0004. I only had trouble with overheating once, when a brand new, high quality water pump as well as the completely rebuilt engine, failed in the first 70 miles. That wouldn't have been such a big deal, but the DW was mad at me that evening for some reason that evening so when she smelled what turned out to be antifreeze, she didn't say a word. Grrrrr.... I didn't notice the quick spike in H20 temp until it started running 'rough'. I shut it down immediately but it had already bent a pushrod and that valve dug slightly into the piston. We've since come to a better plan: If she EVER smells ANYTHING out of the ordinary she promises to TELL ME! My guys checked the pump and even though it said (some really good name), a lesser quality pump was placed in that box.
I still have the OEM (brass finned?) radiator and it works fine. It was professionally rodded out 15 years ago and I change fluids every 3-4 years or so and I only use distilled water. I also have some windshield spritzers ahead of the rad and I just have to turn on the water system from the dr seat. That keeps the temps reasonable till we can get past the high, steep hills. I adjusted the flow so it's not drowning the motor. For the trannie, I have 2 'big as will fit' coolers below the bumper and they get spritzed at the same time. I am religious about looking at trans and engine temps on the dash gauges. May all your radiator trouble be behind you.

[1972VWbus]

Originally Posted by EyezOpen

Finally found an illustration of this unburned charge going out to the exhaust manifold. It is actually a flame thrower of sorts.. Note the "RED" in the exhaust cycle..that is your emission control system of 40 yrs ago at work...

Below is a fairly well articulate article on the subject...and right below is an article on how to cool an engine that needs help..

Understanding How a Smog System Works - Clean Living

If one is handicapping the stock system the late burn may have a bigger negative impact. But with either a vacuum advance or electronic advance one will achieve additional advance at cracked and/or part throttle condition/s which is where the added advance will help lower the EGTs.



Remember load = throttle position

[BA-in-Mich]

A little late to the thread but here's my story. My MH always ran hot from the day I bought it. ( it was 10 years old with 10k miles on it. ) I tried a new clutch fan, Water wetter, I put override switches on the electric fans. Nothing did any good. I read where sealing up the front so that the air coming in through the grill had no where to go but trough the radiator. That helped a lot. I went from 210degrees down to 195 but I had a 180 thermostat in it. so after playing around with it for a few years it was time for the radiator. I took the radiator to get recored. The gentleman that did the work showed me the old core when I went to pick it up. I had a heavy coating of white in the cores. He also stated the the core in it was more for a car than a MH. The original was a 4 row that had 3/8" tubes. He kept it 4 rows but sized it tubes up to 5/8". He blamed the white coating on a certain brand of radiator fluid. It runs at 180 now BUT I had an issue with the clutch fan coming on for some reason randomly. It took a few years but finally figured out that the electric fans on the front was causing a air tunnel straight to the coil on the clutch fan. I removed the 2 fans and my problem went away. That was a few years ago and have not had issue with overheating since.