here is a series of emails that went between me and 914GT. Since Guy had some good suggestions, I thought I should share them here for teh benefit of other V8 guys

Sean
I never did resolve my overheating issues so I m back to the drawing board. I m not sure its purely radiator related. The engine runs strong but.I used to be able to tool around at moderate throttle without a problem. Only racing made it go above 220 but not anymore. The new radiator setup looks cool but did not improve anything. Could my 355 Chevy be failing in a way that makes it run hotter?

Guy
Insufficient bearing clearances could make it run hotter, but that would have not gotten any worse from what you started with. Might check your oil pressures if you haven't already. Timing - too much advance or not enough - can make it run hotter. I'm running about 10 deg initial advance with 4 deg cam advance. Check your distributor vacuum canister hookup to see if you've got full vacuum advance at idle. If it is, move it to a ported vacuum stub on the carb and reset your idle speed and try it again. I've seen timing make a 10-15 deg change in engine temp. Finally, maybe that engine block and heads have a lot of rust, scale, or corrosion causing it to run hot. David over at Desert Hybrids showed me a 327 he had that ran hot, and it turned out the coolant inlets on the front of the block were practically choked-off with corrosion. I think the block hose fittings were aluminum and contributing to it. Unfortunately the only was to find this out is to drop the motor and inspect. I suppose you could try some kind of engine flush and see what comes out of there. If a lot of crud comes out, you might have to bite the bullet and disassemble the motor, hot tank or Amipro the block to get it cleaned out.

I assume you're using the typical RH water pump and the usual pulley size. Make sure that belt isn't slipping. Make sure no hoses are getting kinked when they get hot. If there are any galvanized fittings anywhere in the system check them. I've seen galvanized stuff grow some furry corrosion stuff inside. Replace the thermostat if you haven't already. What lines are you running up to the radiator? Rubber hoses or pipe? If pipe - check for corrosion inside. Brand new radiator - fully shrouded and sealed off so no air recirculation? Enough fan cfm? I'm running two 880 cfm Derales so if you have something similar that is enough. Have big enough inlet openings? I'm running with the cutout behind the bumper plus opening in the bottom of the trunk.

Where are you measuring your engine temp and with what? Is the gauge known good calibration? Where are you pulling the 12V off to feed your gauge? I cal'ed by gauge on 12 volts on the bench, then realized in the car I had an error since the gauge was 'seeing' about 13.5V off the alternator. Duh.

I'm running the about the same engine as you, a 350 bored .040" over. My heads have had some good porting done on them and they flow nice. My pistons and valves have been thermal barrier coated and I think that helps lower some of the heat loss. I wrapped my headers to keep the exhaust gases hotter and less dense, and keep the engine compartment cooler and quieter too. One big difference - I'm running an electric water pump and block water header.

I'm sure you've already thought of everything I mentioned here, but if not maybe give you a new idea for something to look into more. Good luck Sean. I don't have any cooling problems but a little oil leak off the back of the block has been driving me crazy.

Sean
This is a V8 guy thread, too much good info to keep to our selves. Since I have checked almost everything mentioned, I think I will go with the CRUD in the block theory and pursue it . I have driven the car a lot over the last 18 months, even to AZ in Dec. The temps have been creeping up slowly over time. When I installed the RSH Fluidyne Radiator 2months ago, I flushed out the mojo with a hose and it had substantial amounts of rust and chunks. Is there a way to loosen that blockage without dropping the motor? Vinegar? CLR? My water pump outlet adapters on the front of the motor are AL.

Guy
I'm wondering if some of that scale has been breaking loose and blocking the radiator core. One way to tell is disconnect both hoses from that nice radiator, and backflush it and see if anything comes out. If rust flakes, etc. then maybe a good engine flushing would help some, at least prevent loose material from clogging the radiator. Maybe pull the thermostat, bypass the radiator and run the engine 5-10 minutes then drain the water and repeat. I'm sure vinegar or CLR are not going to hurt anything but they may not help much either. Even diluting some pool acid and running it through the system (minus radiator) shouldn't hurt anything for a short time if you drain and flush the block with clean water (take out the drain plugs on the side of the block if you can). But this is only going to take out some of the loose deposits, most of the rust will remain inside. I've tried to clean blocks with a hot-water pressure wash blasting directly into it with the heads off and the freeze plugs removed. You can get some of the shit out but it'll still look rusty. The only thing that makes them look great is that Ampro shot-peen machine.

Now, back to the radiator ... if the flush water comes out clean with no crud then maybe rust in the block is not the problem but I'd be suspicious of those inlet fittings. But damn the only way to get to them is to drop the engine. Might be worth an hour or two time to drop it and take a peek in those holes.

Sean
Crud, crud, crud!
I ran vinegar and water for 3 days, 30 min each day till 230 deg. When I flushed it out, major rusty crud water came out. After this, it took much longer to overheat but the temp still crept up to 230. today I flushed again then filled it with CLR and water. I ran it and left it in for an hour. I was afraid to leave the corrosive CLR in my lovely AL radiator for too long so I flushed it out. Well, a lot of rusty chunks came out. I filled her up with just water and went out about town. 20 minutes into the stop and go traffic, I headed for the freeway. I did a series of sprints from 55 to 90 to romp on her a bit. She stayed at 200 for another 30 minutes of this. When I hit the surface streets, she crept back up to 220. I think a few more flushes and CLR treatment will fix it completely if I don’t clogg the radiator with chunks first.

Blah, blah, blah Are your fingers cramping yet?

before this email chain started, I installed this new Fluidyne with some duck work

custom wire harness was extra

every job needs a helper

the old rad was vented thru trhe floor with an 18 inch fan

I added the fender well holes and replaced the floor

dont make me type you, you thead terrorist
no cramping yet...I know cut and paste

why did Porsche put all that metal in the floor?

Arrr, that be me

no matey, this one

first rad setup

that brass radiator weighs in at about 50 lbs

everything you need to do a V8

Your are obviously missing a left handed muffler bearing in that pic.

blinker fluid low?

take off the manifold on the intake and look for gunk I would think.....

that'll tell you if your engine is gettin gumby..

In all seriousness, I hope you didn't clog your radiator with the gunk.

Andyrew has a great setup with meat thermometers.

He has themat the inlet and outlets of the radiator as well as at the block and heads. This can tell you exactly where the problem is.

I see that dual pass rediator should do the trick but i've also heard that leaky air systems rob cooling power from the radiator.

Oh and if it were me, i'd get me one of those electric water pumps. Oh, I already do... =-)))

Now watch, my little Bebe will overheat on her first day out......

Sean,

Aside from the gunk that continues to be removed from your radiator, it appears your getting close to having acceptable water temperatures.

Roger does have a good point about air in system. I'm sure your running a expansion tank. A picture of how this is mounted would be helpful as well as your fill port.

What kind of thermostat are you running? Do you run bleed holes? These do help in air removal during initial fill of system.

If your not 100% sure about the calibration of your temp. gage, I'd go mechanical for obvious reasons.

With all the filling, flushing and refilling of cooling system, you've got at least two days of burping system to ensure air is removed between every fill. I suggest running the burp procedure and paying attention to what is happening with the expansion tank to ensure as much air from system is removed as possible.

Since your water temperature seems to creep up when you come off the highway and hit stop and go traffic, at what point (temperature) do your fans come on? 179F is the point in which the Renegade system triggers fans. You could play around with a manual switch and turn fans on as you come off highway to see if this helps. It may serve as a indicator that your cooling system is playing "catch up" and could be cured if the fans only came on earlier.

Have you pressure tested your cooling system? I know you don't want to even imagine this, but it is possible that you have a bad head or intake gasket.

With all the crap your moving around in cooling system, don't rule out potential damage to water pump (change in impeller clearance) or impeller blade(s). This unit is 90% aluminum as well. Note: a distilled water/anit freeze @ 50/50 or so mix will assist in preventing creepy crawler growth.

John

forgot pic of water pump. note: this is also a example of how "more is better" is not the case when it comes to applying sealant to gasket surfaces.

QUOTE (rogergrubb @ Jul 31 2005, 12:05 AM)

Oh and if it were me, i'd get me one of those electric water pumps. Oh, I already do... =-))) Now watch, my little Bebe will overheat on her first day out......

The electric pumps really do work nice in this application, despite a few naysayers. They make for a simple setup, especially when used with a water header. As John pointed out above with the Permatex, don't go hog-wild using Permatex anywhere involving the cooling system with an electric pump. And especially do not use Teflon tape.

Sean, et. al ... would you mind if I used some / all of your comments in my 914-V8 conversion manual ???

thankyou all for your input. I'll try to fill in teh gaps this post

I put this up here for 2 reasons.
1 to share this experience with other V8 guys so they can learn from my mistakes. Go ahead and use any pics or text that may help
2 to learn from all yous guys that have chimed in on this thread.
Guy told me to drop the motor. by the time I'm done with all this flushing around, I could have had the mojo out. I like the idea of removing the intake manifold to inspect. I think that will be next if I cant get it to behave on a hot summer day

I have a manual fan switch

I'll post a pic of the exp tank mounting

I apply all sealants sparingly, using only a fine paintjob-like coating to the surface to be sealed. you only need enough to compensate for irregularities in the 2 mating parts' surfaces

Moroso high flow 180 deg thermostat. it has some flow even when closed

check out my air burp system on teh intake manifold. it goes to all teh high spots in teh cooling system

I still need to check teh blinker fluid

Andrew: please post pics of your setup

How do I pressure test the cooling system? If it will reveal a problem, I want to know about it BEFORE I damage my mojos guts

I think I need some Edelbrock AL heads. If I can go faster, perhaps it will cool better

the jumping monkey stole my left handed mufler bearing

fdgfrd

one capillary goes to teh top of teh radiator, the other goes to teh top of teh intakes water gacket

radiator air bleeder

Sean, all my pics are in my sig.....

new Renegade pump

old boat pump

vhv

Sean,

Before you start changing parts, start with baseline and make absolutely sure you have:
-system is FULL of water
-water IS flowing and there are no obstructions or air pockets


I've seen old copper Camaro and radiators that were smaller than the front trunk cool sufficiently.

Cooling efficiency is all based on flow vs. heat exchange rate. You dial that in and it should work. Everything else supports that.

steel cooling lines run under rockers with no fancy up and over bends to avoid air pockets

Felix: how do I confirm that?

Andrew:
I really really like your GT 40 style air outlet in teh hood. Although I was all over your car at WCC, I did not observe your temp gauge set up. do you have pics of that?

You know those old style thermometers that you stick in pots and pans, or meats?

Ok, stick in the radiator fins on the hottest part of the radiator, and one in the coldest part of the radiator...

Buy 2 new ones so you know there the same.

maybe I'll buy one of those IR thermometers. I cold use it for teh radiator, engine block and even my tires at the track



look what I just found
feed me, feed me

Whats cool with the meat thermometers, and the open hood, is that when I would get out of the car, I would just walk up to the side of the car, look in and see the difference between the 3 thermostats in the car.

Was really great for when I was first testing the system.

BTW, I remember that pic... lol

My tach went out, and my brake lights went out right before stopping there, and one of the guys lent me a fuse to fix the bugger with.

Right after mike z said that my brake lights where out.... lol

there were parts flung all weekend at WCC. my fuel pump relay went out on the fun run on Moholand Dr. back at teh hotel parking lot I shouted out and 5 relays apeared instantly

Hey, gimme back my relay, hahaha! It's cool that we are such a tight knit group, eh?

QUOTE (sean_v8_914 @ Jul 31 2005, 10:27 AM)

maybe I'll buy one of those IR thermometers. I cold use it for teh radiator, engine block and even my tires at the track

Sean,

I've experienced various problems with the cooling system in my car until understanding how it worked and various troubleshooting techniques. Bought one of those IR guns and found it easy to pin point different temperatures throughout the system. Although this can be a point of reference, the bottom line is the numbers don't explain the problem. The $175 IR gun did not do that but as you said, could be used to determine tire temperature.

John

OK, school me
I got my pencil, gimme something to write on

QUOTE (sean_v8_914 @ Jul 31 2005, 09:31 AM)

I'll post a pic of the exp tank mounting check out my air burp system on teh intake manifold. it goes to all teh high spots in teh cooling system How do I pressure test the cooling system? If it will reveal a problem, I want to know about it BEFORE I damage my mojos guts

Sean,

Looking at the pictures you have posted, it does not look like you have a expansion tank. What I see and the way the hoses are plumbed from the aluminum tank, (from your description......to top of radiator and one to intake) what you have is a fill port and will work great for just that, but will not work as a expansion tank.

I recommend adding a tank similar to the picture attached. This works as a true expansion tank by being open to atmosphere. It allows water and air from your cooling system to collect there as the pressure determined by your radiator cap setting. Then as the system cools ONLY the water is allowed back into cooling system.

For about $10 you can buy the tank, mounting bracket and extra clear hose. Connect hose at bottom of new expansion tank to hose at the top of your fill port and you should see improvement. I'd go to the radiator where you had the hose on top of fill port routed and use the fitting on top of radiator as a place to purge air during burping procedure. Add a petcock fitting if required.

All of this is what I learned from the Renegade system and exactly how they do it.

As far as pressure testing cooling system: you can rent a tool from your FLAPS to do this. You'll get a small hand pump equipped with gage and a fitting to attach to top of your fill port. The instructions will tell you how to perform operation and it only takes about 10 minutes. You'll basically just pump up your system to about 20 psi or so and wait for 10 minutes. If you see a decrease in your original pressure, you've got a leak. Could be a hose or something else external. Worse case is a bad head or intake gasket.

John

does the plastic tank need to be mounted at the same height as the filler neck? mine is odwn low

the brown hose to the left of teh radiator cap goes to a plactic bottle. it is ismilar to yours but mounted low since the Jacobs computer is in teh way. prehaps I should move the ignition system to teh rear trunk to allow mounting of a plastic tank like teh one you showed me here

Glad to hear your running a expansion tank!

The expansion tank needs to mounted as high as you can get it since all you have is a small amount of vacuum to pull water back into system during cool down.

The expansion tank can be used to determine flaws in system and I recommend having something that you can see (water increase/decrease) as your troubleshooting. If your not pulling water back into system as it transitions from being hot to cold, you've got a leak in system and allowing air, not water back in. FYI, the tank you see in my picture is the larger version......where I picked mine up there was the same rig but about half size.

What about your gage? Are you sure your getting accurate readings?

John

travis: thanks for teh relay. Sue and I were just looking at this photo and talking about the nice guy that rushed up with the spare parts that day. we broke down up there and didnt even care. the views were amazing as teh ride its self. we never got out of 2nd gear

John, I see teh level of water change during cooldown by about 10-16 oz after a purge and re-fill. does a radiator shop do a presure test of teh system? I think my fill tank has an air leak at teh neck. it girgles there a bit

it fizzles under the radiator cap about an inch below where the neck joins the body of teh AL tank

who tig welds in San diego? how much should I expect to pay for that bead around the neck

Sean, you might get away with just using some high-temp epoxy to seal that air leak, since it's just a small seam between the two parts. I'm assuming the upper piece is crimped on somehow and doesn't need a mechanical repair for strength.

QUOTE (sean_v8_914 @ Jul 31 2005, 06:45 PM)

it fizzles under the radiator cap about an inch below where the neck joins the body of teh AL tank

Sean,

If you have a leak in the fill tank, your expansion tank is not able to do its job. The leak in fill tank will allow air to enter system during cool down. Coolant draw from expansion tank is further aggrevated by being mounted low as described.

With this situation, you'll never get the air out of system necessary to prevent overheating. You could have just about any auto shop do a leak test of cooling system but you'll have to wait for system to cool to allow removal of radiator cap unless you have some other means of doing so. As I mentioned in a earlier post, this tool is available for rent for about $10/day and may come in handy if your going to attempt repair of fill tank with some type of expoxy. BTW, I recommend JB Weld (if your not going to weld it) only after sanding metal your going to apply material to. Obviously, welding this seam is the preferred method.

Once you've got all leaks repair, monitor expansion tank level for several days. It will take several "burp sessions" to remove initial air in system and after this point you should be able to see level in expansion tank stabalize to the same point everytime after cool down. Note: cool down takes several hours to occur and I use "overnight" as my test period.

John