Overheating issue

COMETIZED · Feb 21, 2018

Hi Nick:
Just noticed in one of your earlier ' posts ' you mentioned that the bottom radiator hose was collapsing when you REV the motor .. and then I noticed you have a FLEX FAN ..... Dangerous .. We lost a guy about ten years ago when he was REVVING .. ' HIS ' motor while standing near the car and the FLEX FAN let GO and one of the blades sliced his neck and he Bled Out before they could get him to a ER . I read where you have a new radiator .. If you look in the Salvage Yards.. Try to find a VOLVO fan setup with the shroud .. William on this forum has one and it works just great .. In the meantime .. DON'T REV you engine and be anywhere NEAR the trajectory of the fan blades. They are DANGEROUS .. I have one hanging on the wall that I purchased NEW years ago .. and I'll NEVER use it ... or sell it
to anyone else that could have a problem ... It's a REMINDER !! Just a word of advice from another enthusiast !
Cometized
(Chip)

Russell · Dec 9, 2020

groberts101 said: ↑

ok.. sounds like you've got some bigger issues going on here. It might sound a bit gruff to say but I mean no offense and typically just shoot from the hip in an effort to save people I care enough to try and help more time and hassles. No hidden tones, no holier than thou attitude, simply spending my time to try and help and calling it the way I see it. Not nearly my first rodeo building and tuning engines either.

First off.. a motor is VERY forgiving. There's some science involved.. but it sure ain't rocket science and no degrees required either. They can puke water, oil, gas, run on 5 cylinders, etc, etc.. and STILL get you around semi-reliably if you have all those backup fluids and funnels sitting in the trunk to keep you from burning it up completely. Hell.. run it down to a single quart in the pan and it'll still run for a long time on that minuscule amount of jet black syrup. Many of us have driven a few and seen countless hundreds of others that seemingly defy the laws of physics as their owners keep driving them into the ground month after month. That being said.. and as mentioned before, even if you have some crud filling the entire lower half of the block(again.. some guys do that on purpose with engine grout) it's highly doubtful that a brand spanking new radiator would suddenly plug up completely and give the same exact issue as if you had done nothing to fix the issue. No way no how will an engine quickly go to 240 with the newer components you have installed.. UNLESS.. there is some other underlying issue that's causing it to do so. Water pump spins and circulates water/coolant though the block, heads, manifold and out through the radiator. Doesn't need to be even close to perfect to keep an engine from shooting up to 240 in short order. It seems MUCH more likely that you're missing a head gasket leak(likely from a warped head/s if the new gaskets did not cure the issue), cracked head(could even be in the exhaust port which the exhaust systems pressure would not be high enough to contaminate the testers reading from any intake vacuum source), have them reversed(or maybe even the intake gaskets are wrong style/reversed). Takes a severely plugged system to do what you're describing here.

My last bit of long winded advice is this.

Lose the fancy high-tech tester and do a simple pressure check at the filler neck. Many big-chain auto parts stores rent loan them out for free these days. There are many locations for compression to enter the cooling system and not all of them will have spent exhaust gasses present. A simple cooling system pressure checker doesn't care about gasses.. only the integrity of the cooling systems sealing points. The KISS rule applies here in spades.

You didn't say anything about numbers for vacuum readings and "normal" is usually ALWAYS lower then the engine would prefer. No manufacturer wants to put timing into an engine that results in smaller margins for people who don;t rightfully and religiously maintain their cars engines. Plus, even before catalytic converters where a major concern, none wanted to tune their engines in a way that NOx starts going through the roof due to higher amounts of spark advance. Funny as it sounds, they'd rather you contaminate your oil more quickly(which pistons, rings and cylinder bores really hate) and send more raw fuel out the tailpipe than drive up the NOx readings with heavier timing advance. It's the old monkey see monkey do thing and gets perpetuated. I know this to be fact and have proven it to many over the years. Even guys around here have cured overheating issues like yours by doing nothing more than optimizing their initial timing and changing over to a full manifold source for their vac advance pots. And some of those fixes came AFTER throwing many of the same parts as you have at a nearly identical "overheating" situation.

Timing advance. You seem as though you may be resistant to the idea of what an engine truly needs for spark advance at idle, especially with a bigger than stock camshaft, but I will spend some time to try and edumacate you a bit more. This engine, almost ANY engine despite some of the newer combustion chamber efficiency increases(look at the timing tables of an EFI engine and you will see upwards of 50° or even more), wants/needs/MUST HAVE much additional advance due to the very slow and sluggish low density mixture speeds at low idle/induction/piston speeds. Add bigger smog style chambers, thick/oversized head gaskets(let me guess.. 4.100 bore gaskets?.. YUCK), lack of sufficient squish pads(smog heads), too much deck height, and then top it off with a bigger than stock cam that makes the incoming mixture even lazier and what do you get? INCREASED TIMING LEAD REQUIREMENTS AT IDLE AND PART THROTTLE. In fact, IF you are running the distributors vac advance pot from a ported source?(and seems probably since you didn't define that fact).. I would go so far as to put money where my mouth is that this motor has far less timing and manifold vacuum than is optimal. Should it start overheating now when it didn't prior?.. no way. BUT.. tunes don't stay identical over time as components wear out and electrical parts build continually build resistance either. You have absolutely nothing to lose and everything to gain by simply swapping that little hose over to a full manifold vacuum source. It may not fix this issue but troubleshooting rarely gets easier than that simple task. Spark lead will go into the low 30's, idle speed will increase(again, you'll need to adjust idle stop and mixture screws to dial it back in), manifold vacuum will go up, EGT's will go down along with their related coolant temps. Manifold vacuum on a semi-healthy engine(which seems somewhat debatable here) with mild cam should be AT LEAST 17-18 inches. With fine tuning of both ignition and fuel curves it is possible to reach upwards of 20 inches or slightly better even with a mild cam. As some members I have helped around here will attest to.. the difference in how an engine runs, and the reduction of heat it puts into the cooling system can be startling to say the least. Throttle response and mileage gains are a certainty as well.

My main point is this. If you're logic is not sussing out the issue and you've thrown everything but the kitchen sink at the problem?.. change your logic. Or another way. If the result doesn't match the theory?.. keep changing the theory until the results line up. Preconceived notions will often get you nowhere if you hang to them too tightly. Wipe the chalkboard clean and start over based on the physics alone. Good luck and hopefully something within all this babbling can help you figure it out.
Click to expand...

THANK YOU, groberts 101...Whenever my 'inner mechanic' looses his logic, ( often ), I read your posts...spanked him good, now I'm ready to get back to my mav problems....sometimes, with even simple diagnosis, I feel like a piss ant gawking at an IBM computer...

rickyracer · Dec 9, 2020

So what ever happened? I know this is an old post, but no ending.

COMETIZED · Dec 17, 2020

Hey Vomit Comet : ( Don't know your name)
I read that you have a ' Flex Fan ' ..I've mentioned this before , but it bears repeating .. We had a member that was winging the throttle on his Maverick with the Hood Propped up and the flex fax ' let go ; and a fan blade detached and struck him in the neck and severed his jugular vein . He bled out and died in his front yard ( No Joke ) His wife still drives the Maverick with another type of fan . Ditch the fan friend ..it's not safe !
Cometized
Chip
P.S. I"d flush the radiator also.

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Overheating issue

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Russell Orejano

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