"Charlie" has Overheating probs- Here are my Clues and please chime in with opinions!

-
Gen2Cudas

Gen2Cudas

Well-Known Member
Joined
Mar 21, 2009
Messages
275
Reaction score
10
Location
central Texas
icon_minipost.gif
Posted: Thu Jul 08, 2010 11:27 am at Slant Six Forums too-

Post subject: Slant 6 Dan and all, I would like your help- overhtng clues

Morning Guys and Gals.

Haven't been to the Forum lately as life has intruded- as it does all. Gonna go check on Red at the body shop this week. . .slow progress.

I am with a whole day to try and fix an overheating problem with Charlotte (aka "Charlie"), our slant 6 powered 'vert. I think it will turn out to be the head gasket, but I wanted second and third opinions before I tear the head off!

Background: So called Super 225, bone stock, 1 barrel (thanks Dan! The Carter works great!). We have been just driving the thing as it sat for decades without. Done the fuel mods, got the timing advanced as far as I can (44 degrees total, no detonation, runs good), just fixing what fails as you put a car back into service after so long sitting up. . .

160 stat with a oversized aluminum radiator and new pump. Has been running at one third the temp gauge for 7-8 months, winter and summer; we have made 300+ mile highway trips with no problems, lots of city driving in Dallas and Austin where she only gets to mid range idling at the lights. Overall, just quit looking at the temp gauge- problem solved.

Flash forward to about 2 months ago- driving highway at 75, been on the road for about 40 minutes, just happened to notice the darned thing was up past the midmark. Pulled over and checked the water- very slightly low but visible. Let her cool, started her up, made our stops, made it back 40 minutes north- running higher but manageable at 60-65 with the heat off the day- back down below 90, that is.

Checked everything you would check- not leaking, not "using" water out of the radiator, no water in oil, did another flush and run through the block, new lower hose that looked like it was collapsing a bit, fresh antifreeze and water, rechecked the timing and reset for advanced, etc.

Now, it starts hard and spits and coughs until it warms up, but it runs cool at idle (1/3rd of temp gauge). Sat at idle for over an hour while I fiddled with the timing and all. You drive it about 10-15 mins though and it starts to get hot- not all at once, but gradually will go to 3/4ths-7/8ths temp gauge before I run out of nerve and stop and let it cool. I smell a strong odor of ethylene glycol on occasion, but it doesn't seem to be losing any coolant out of the system. Do seem to get a bit of excess condensation out of the tailpipe on startup, but does not smell/taste sweet (I tried it). Does seem to dry out when warmed up to operating temp. When hot, I do hear steam expansion "bangs" in the system, but the water level never seems to drop enough to see. Can't smell exhaust in the water myself and no bubbles I can detect. Good flow at idle and with the throttle held down to about 3000 rpm.

Just pulled all the plugs for the second time- hoped to see some rust or something water related- but plugs still seem fine in color and wear except for one- a little discolored is all.

Just did a compression check dry and wet this morning and compared it to the numbers in my ancient Chilton manual- the highest number does not get on the chart after wet test (130 lbs) and the lowest is 115 after wet- was 100 lbs on the dry test. Note that my compression tester is NOT calibrated- just try to go with high to low differences. Not really enough difference high to low to be noteworthy- though the back three cylinders seem to be lower than the front three (118, 115, 125 versus 130, 128, 130 wet.)

My unexpert guess is a slow leak of combustion gasses into the water jacket through the head gasket- just enough of a leak to warm up the coolant beyond what the radiator can cool at speed. I'm guessing that putting this probably un-rebuilt little darling back into full temperature service finally put the head gasket OUT of service. I am hoping that since I don't find water in the oil that there is no crack in the head, piston top or cylinder wall. . .and I am hoping that not enough water enters one or more cylinders as it cools to materially rust the cylinder walls and kill my piston rings off. . .

Please, look at the above reasoning chain and tell me if I might be missing something else to look at.

Also, it would be nice to know just what a Slant 6 ought to have for normal compression pressures minimum and maximum, if anyone knows.
I've used this same compression tester on my 318 and it runs 170's to 180's. 'Course that one has more base compression. . .

Mike
spacer.gif
 
First thing I would do is put a new after market temp gage on the slant, My factory temp gage 66 170/6 has lied to me a couple times 8)
 
Did you have the engine running when you refilled the radiator?
You might have an air bubble in the system.
Just my 2 cents.
 
thats a lot of timing under load.44*?

that cylinder pressure is weak, running fat on top will run hot, then the timing...

of corse running lean will have it hot.
 
memike said:
First thing I would do is put a new after market temp gage on the slant, My factory temp gage 66 170/6 has lied to me a couple times 8)
Click to expand...

Memike, I would kinda hate to go that route- the thing may well be lying now (or the temp sending unit may be going away), but I'm trying not to hang any extra gauges in the thing for visual appeal (or lack thereof). I am contemplating running it back to overheat and checking the coolant temp with a thermometer- if I can safely get the cap off!
 
irelandmoss said:
Did you have the engine running when you refilled the radiator?
You might have an air bubble in the system.
Just my 2 cents.
Click to expand...

Yeah, did indeed. Filled it first, then started it and let it run while pouring additional coolant in- even idled it up a bit and added more as it "pulled" the level down a bit so I could kinda overfill it.
 
1wild&crazyguy said:
thats a lot of timing under load.44*?

that cylinder pressure is weak, running fat on top will run hot, then the timing...

of corse running lean will have it hot.
Click to expand...

Yeah it seems high to me too, but-

Did the timing from an article I got in Mopar Action. Erenbergher (?) made a great argument that Ma Mopar set all of ours a bit too retarded. So, did what the article suggested. That actually fixed the previous tendency to overheat it had when I first got it back on the road. Seems to run great and cool- or did until recently.

As a matter of fact, I have had to re adjust the fuel to more at idle to get it to run smoother since I started having this problem crop up. . . .hmmm.
 
Gen2Cudas said:
Memike, I would kinda hate to go that route- the thing may well be lying now (or the temp sending unit may be going away), but I'm trying not to hang any extra gauges in the thing for visual appeal (or lack thereof). I am contemplating running it back to overheat and checking the coolant temp with a thermometer- if I can safely get the cap off!
Click to expand...

I under stand, I don't ether :happy10: you can put a gage under the hood would be out of sight and can be a second opinion, I do agree that the timming and running lean like 1wild&crazyguy said and make sure you burp all the air out of the engine.
 
memike said:
I under stand, I don't ether :happy10: you can put a gage under the hood would be out of sight and can be a second opinion, I do agree that the timming and running lean like 1wild&crazyguy said and make sure you burp all the air out of the engine.
Click to expand...

Not a bad idea at all under the hood! I wonder if I can tie it in parallel on the same sender?
 
I don't know, I would ask a /6 tec and see if there is another place on the block to get a reading, I wonder if a top radiator hose could be made to hold a thermal coupler temp gage " non electrical"
 
Well, decided to go for it- tearing down the head to the gasket, will let you know what, if anything I find. Easy enough to get down to just the head bolts in about an hour and a half, drinking a beer before I do the "surgery". Daughter is assisting.
 
Check your radiator core while you have it down. I have seen a "plug" of junk let loose and plug a brand new radiator in a matter of minutes.
Frank
 
Did get the thing pulled down to the gasket- taking pics all the way, will try to post.

See indications that the gasket was failing- paper separating along one edge between the #3 and #4 cylinders, some signs of darkening along the metal toward the water jacket passages. . .

. .and about half the water passage holes either completely or partially blocked in the head by crud. Damn the previous owner for neglect! Heck, I would have been hot too if I was using only half the water flow- but it wasn't until the gasket started leaking combustion gasses into the same slow water flow. Don't know how the thing didn't crack or warp. All valves look good, the heads look fairly clean as to the valves- even see nice ash on them from the lead additive I've been putting in.

The cylinder walls are obviously original size, never been cut- so this thing is on its original unrebuilt motor.

Am putting the head on now, will try to button her up tonight. Let ya all know.

Thanks for the input and support.

Mike

Charlie's gasket change 004.jpg


Charlie's gasket change 005.jpg


Charlie's gasket change 006.jpg


Charlie's gasket change 007.jpg


Charlie's gasket change 008.jpg


Charlie's gasket change 009.jpg
 
those pistons don't look stock to me.

I have 3 stock 225's sitting outside right now and none have the belley button in the center, oooooold forged pistons do though.
 
This is a post also happening over on Slant Six....


It didn't help after all. Got her buttoned up, timing set, valve lash reset, idling smooth- and took her out yesterday and same deal. Runs nice, but after a 10-15 minute highway run it starts to creep up in temperature from 1/3rd of the gauge (160 'stat). Once it starts up past the halfway mark it continues to heat even if you slow down to 20-30 mph. Nice afternoon/evening about 83 degrees F. I let her get nearly to the last tick this time- and once shut off, steam and water out the outflow, temperature of the outside of the radiator about 180+ with another thermometer I have that goes to 220 degrees.

Moved the timing more advanced- up to 15 degrees BTDC- it controls the temperature better- actually will stay at 1/3rd to 1/2 temp gauge and more importantly, it will cool back down from a speed run like it ought to. . .unfortunately it won't idle without a miss and is hard to start cold. I can't hear detonation- but I'm not sure that it isn't occuring silently. No indication of detonation on the plugs either- nice clean light brown, no overheated ceramic or welded looking electrodes. . .Ran her at 44 degrees total advance (preset, mechanical, vacuum) for 8 months and she did great- got that idea from Mopar Action Mag and Erhenberg article from last year. . .dunno, could be the timing mark is slipped around on the vibration dampener too and all my calculations are squat! Looked close when comparing the distributor position though. . .

Now, what about a crack in the head? I wish I had taken it to be Magnafluxed while I had it off. Did closely inspect the thing, but. . .sigh. Look at previous pics- no obvious signs there.

Before I go to the time and expense of disassembly (again!), will try to see if combustion gases are getting into the radiator water a 'la TopHat's (/6) suggestion and procedure. Right now, going back to re-check the simplest stuff- good pump flow, clear water, clear radiator, flush and fill, etc.

Quick answer to a few other suggestions: no, no A/C so no condenser (one day!); exhaust is 1 7/8 short stack welded to 2.5 from the outlet point all the way back and new, not crushed; there Was crud inside the block when I replaced the freeze plugs, but we dug all we could out and then flushed- and the damned thing did run cool for over 8 months. . .? Radiator is a new (1 year installed) 3 row made for a V-8 and fills the hole in the front firewall completely like on my other one. Kept the little fan since it was cooling fine before late May, drat it!

I had friends with this problem in cars before and felt sorry for them having a "problem child" that overheated. . .what goes around. . .

Keep those thoughts and suggestions coming! Appreciate the help.

As far as the head gasket and the pistons being aftermarket are concerned, maybe it Has been overhauled- my first Slant dissection(?), as it were. Wish the previous owner was savvy and concerned enough to "pickle" the darned thing properly for storage!

Thanks to everyone with a thought!

Mike
 
More food for thought. . . .

I was running a 160 degree thermostat- took it out for the flush I did today. Likewise, went and borrowed a system pressure tester and hooked it up- steady as a rock pressurized, even when the engine was running and tried and tried to get it to shake the needle with the motor at normal temperatures and RPM up to 4000-5000 and held. Nothing. If a crack were there and opened with the heat, I should have seen something like a pulsing into the water and shaking that needle. Didn't even pressurize it above the 15-17 lb point. So, the head and gasket seem good.

Drove the borrowed tool back to the AutoZone- ran on tap water only, got no hotter than 1/3rd temp gauge. Gotta be the 'stat- it isn't even in there any more! That'd be embarrassing!

Then, took it out and ran it on the highway-65-70 plus for 5-8 miles- temp crept up to 1 tick past the halfway mark- still getting hotter than it should. . .

Pulled over for gas, restarted it- needle 2/3rds with the stop, then as the water circulated, dropped right back down to 1/3rd. However, while driving now at 50-60, needle started its creep back to halfway. . .about a 5 mile drive back to the house.

Driving me to drinking, it is- and now I am out of beer!

Then, it dawned on me- TWO sources of heat being inputted into that radiator- the engine and the automatic transmission.

Just how hot does the transmission operate normally? Just pulled the dipstick for the tranny- the stick is plenty hot, but the oil is still clear red and didn't cook my fingers. . .but I got thick hide there too.

Whatcha think?
 
pull the threaded plug out of the block on the passenger side with the water full. see if water comoes out. i had very similar issues. this car sat a long time and i dont know if critters made a nest in the engine or what but there was tons of **** in the cooling system and i would flush and flush till clean. when i would take it on the highway after a few cruises it would start to run hot again. flush till clean and it would keep repeating. i got an idea, pulled the plug and i had to stick a screw driver in it till water came out. then i blasted the hose with high pressure into it till clean water came out. no more issues. i did have the same thought about th ehead gasket but never pulled the head. it would idle all day long or even drive around town but on the highway that stuff would loosen up and collect in the rad.
 
Well, it is a new day- I think I will give that a shot, thanks James. My wifey had a similar suggestion through a freeze plug.

Will put it back up on the ramps and give that a try this morning- will let you know.

Mike
 
i did it from the top no ramps. i think the plug has a 9/16 head
 
I believe you hit it James- I hope this is all I find:

Took the plug out- no water. Black, charcoal looking stuff, dry. Hacked at it with an auger bit, screw driver, punch. . .finally got water. Been spending a coupla hours scratching around inside with coathanger wire trying to bust this stuff up. . .flush and fill, blast with a high pressure hose, run the engine at speed and blast it back out. . .

. . .and know I am not making a big dent in that crap. Can't reach much with the wire. Currently trying to turn it into something more moveable with 50/50 vinegar poured straight into the block. . .

Anything else someone might suggest I try? I do not want to pull this thing and hot tank it anytime soon!

Mike
 
keep flushing it and driving it. just keep an eye on how dirty the water gets an how the temp guage behaves.
 
You must log in or register to reply here.
-

Back
Top