I have no idea anymore... [85GT coolant issue]

[Tempest]

Alright, so my 85 GT had been having an issue where it would fall on its face around 43-4800 RPM, backfiring. The lifters were ticking, and it had a few symptoms indicating it was running lean. Still had good power, 0-60 in about six second, maybe a little less. Ended up replacing the carburetor, as it had a few other problems as well. Immediately after replacing the (OE) carb (with a street demon 625cfm) and doing some timing adjustments, it ran great. (probably not important, but ended up disconnecting the vac advance, it ran better) Really crisp throttle response, etc, as expected, I got about five and a half seconds. Oddly enough, the lifter tick stopped as well, and it has yet to come back. (Could have also been an oil change a few days prior) A couple of days after, one (very cold!) morning, the heater refused to work. It has always taken a good 10-15 minutes to warm up, so I start driving it to school, being careful not to rev it up (yea... its my daily... hopefully not for too much longer.) and still no heat. After school I check the coolant, a bit low. I put more in. Heater doesn't work. It eventually starts working briefly, off and on. Power seems a bit off. Coolant is mysteriously disappearing, car starts overheating. I start driving it tamely. Coolant is STILL disappearing. I replace thermostat, its still overheating. At this point I'm just putting a ridiculous amount of water in the radiator every day. I parked it about a week ago with the intentions of tearing the engine apart this weekend, expecting:

-A blown head gasket
-A cracked/warped head
-A cracked block (was really worried it was this, its been really cold, and I'm not sure if the coolant was a perfect 50/50 mix.)

Well, we took off the all the accessories, the carb, intake manifold, heads, etc, right down to the block.... And all the gaskets seemed fine. Heads looked OK but they could be in better condition, same goes for the valves. Block looks fine too, we inspected everything pretty hard. Theres some orangish yellowish crap in some of the heads' passageways. At this point I hope its a crack somewhere in the heads allowing coolant into the combustion chamber, but I think that may be unrealistic and optimistic. (Replacing the heads was already a major to-do) Am I being irrational in also fearing a crack is somehow in the block? There is no oil in the coolant, and no coolant in the oil. I really have no clue what it is.

[wraithracing]

Not to state the obvious . . . Is the Water Pump actually pumping coolant?

That would explain the overheating, the lack of heat coming out of the heater core. The loss of coolant would be due to the system pumping the coolant out of the overflow tank due to temperature and pressure.

Always check the simple stuff first. We are all guilty of this. I just had similar issues with my daughter's car. In the end it was a clogged up radiator that wasn't allowing the coolant to flow properly. Which could also be your issue.

Bottom line doesn't sound like you have a major issue to me, sounds like either a radiator or a water pump issue. Good Luck!

[jjltthomas]

Yeah. Ive seen water pump blades that have deteriorated over time to nothing. Still spins good but with no blades theres no movement.


Sent from my iPhone using Tapatalk

[2nd chance cobra]

I saw a waterpump once that All of the vanes had been rotted off due to coolant system neglect. It was a tricky one to find. Only saw it once is 12 years on the line, but it can happen

[homer302]

I have to agree with everyone above. If there is no coolant in the oil, then you don't have a cracked block or heads. A blown head gasket could be small enough where you send it out the tailpipe and not see it in the oil but you say the gaskets are fine. I would say your issue is a water pump that the guts have fallen apart or a clogged radiator or even a bad radiator cap gasket. Any of those would explain your symptoms and could be fixed for less then $100 and less than 1 hour labor at most. A bad radiator cap gasket will not leave puddles anywhere but won't allow the system to build pressure, (causing the heat to suck). I JUST experienced that late last year and although it took a few drives to troubleshoot, I did end up finding it and it was a $10 fix. When the coolant gets sufficiently hot, it will just evaporate coolant out the gasket without any real symptoms other than the smell. At least I know that's what mine did.

[ashley roachclip]

You really should have at the least , rented a coolant system pump, and then you would have been able to see for sure , where the leak was coming from .

[bwguardian]

The orange substance is rust. Depending on how much you are seeing it could have your radiator to the point it is not circulating properly. Run the engine until it warms up with the radiator cap off and see if you are getting circulation. This may take a little bit for the thermostat to open. If not, I would at least pull the radiator and back wash it and think about having a shop rod and clean it. While you have the heads off, I would back wash the coolant passages in them also. This doesn't explain you loosing coolant though, as have most of the posts above. If the head gaskets look good and you don't suspect a cracked head after looking at them, then look at the freeze plugs. If they are the original metal units, I would highly suspect them being rusted through. If still nothing sticking out, I would take the heads to a shop and have them magnafluxed to check for cracks unseen by the human eye. Are you getting any kind of smoke out of the tail pipes? Actually since you have the heads off, is there a difference in color of any of the combustion chambers? What does your oil look like when you check the dipstick?

[Matt J]

To add to what everyone else has said, if the coolant isn't circulating, you might find the radiator isn't hot, as is the case for the upper and lower hoses (they should both be hot). If the radiator is blocked you might find it's hot in spots but not uniformly. Is coolant boiling out into the overflow tank? It should be filling that sucker up if it's overheating. Check hoses and radiator for leaks. Is there any coolant on the top of the block where the thermostat elbow could be leaking? Any coolant dripping from the weep holes on the bottom of the water pump? Finally, what is the temp gauge telling you? Does it change as the car heats up? It really does sound like the water pump isn't working. Hopefully yours comes off in one piece...mind didn't.

[Tempest]

The oil looks normal, as does the coolant. Whoever last had the car had a plumbing pipe stuck ito the intake manifold, and there's some coolant leaking there, but now that I'm able to remove it I'm taking that out. The water pump is off, anything I should look for? I'm going to a head shop today to have them check out the heads. Additionally, my temp gauge is broken.

[wraithracing]

At this point, it is preventive maintenance to replace the water pump. You can double check the current pump to verify if the impeller is there and actually rotating with the front snot. Look for clogs, etc.

Bottom line a new pump is cheap insurance when you are this far along. I would also get a new temperature sending unit to help diagnose your vehicle too.

Nothing wrong with having the heads checked, but I doubt you have an issue based upon your comments.

[Tempest]

I have always been told to have the heads remachined when pulling them out for the first time in a while, so I was going to have them do that anyways. The real decision is if I want to build up the 302 or get a stand and keep a 351 block on it and build it up the way I want to, removing the stress of doing it all in an engine bay, plus not worrying about the 302s limits. But if I keep the 302, then new heads would be in order, and now would be the time to do it.

[erratic50]

I had a impeller shaft seal on a water pump cause my car to act like this. Would lose around 2 quarts 50/50 in 3000 miles. It eventually revealed itself when the leak got worse.

if you have a leak you are sucking air. Air pockets don't cool engines properly or heat interiors properly.

If you tear off a water pump, ideally get your motor running with water again first. Clamp the top hose and get it towards the high side of operating range. drain it while the engine is hot and get right to the housing bolts. The bolts that go into the block are notorious for twisting off - especially driver side pump to engine bolts by the power steering pump bracket. I've done 3 water pumps and twisted off bolts on 2 before I learned this trick. You've been warned!

[cb84capri]

Do you have any piston tops that look really clean? The orange-ish yellow-ish snot could be rust and stop leak.

5.0 blocks like to crack like this:



My old 302 did this too, never had any issues from it even after taking the heads off/on like 4 times after it developed.

Cale

[Tempest]

Got the heads back from the machine shop, turns out there was a crack in one of the coolant passages... Hopefully the problem will be gone when I put everything back together. Waiting for radiator, water pump, and head gaskets to come in the mail.

[erratic50]

Thought I'd check back in - I hope you get your 85 back to fighting form soon!

Instinctively, I almost started asking if there are any codes. It's carbureted, right? Still could be ignition parts or distributor pickup maybe. I had a seal fail on my 86's dizzy a few years back. It would run OK but not great. And I eventually had oil leaking out from distributor housing and cap.

Good time to do the usual suspects. Plugs, wires, cap, rotor... Double check distributor, etc. Do not install ANY part without testing it first. Known good parts off the shelf or from a buddy's car are preferred over new when trying to pin down this type of issue.

Good luck!

[Supersonic G.T.350]

Not to sound like a douche but It's not going to be gone if you put a cracked head back on... You didn't say whether you got a replacement set or not. Personally I'm your shoes I'd find a set of GT40's from an Exploder, have them milled and use them. E5 heads are nothing to write home about anyway.

[Tempest]

When he remachined them he fixed the 'crack' it was more just the entrance to the passage had worn down and he filled it with some more metal or whatever, I don't know anything about machining

[droopie85gt]

Ditch those heads. Iron heads are cheap and hard to fix if you don't know what you're doing. GT40 heads are a cheap quick upgrade. GT40P heads are a bit better but you would need new headers/exhaust manifold.

[wraithracing]

Don't know your relationship with your machine shop or machinist, but I would need a more detailed description of how he "fixed" the head with the crack.

As stated, iron heads are not often easy to fix and in my experience weren't necessarily cheap repairs either, so I would need to know more before installing them back on the car. Good Luck

[plumkrazy]

at the thought of fixing common stock heads. But sometimes you have to do what is fastest and easiest at the time

[Tempest]

I'm friends with the machinist, he only charged me 25$ to remachine both the heads and fix the warp/crack

[plumkrazy]

I'm friends with the machinist, he only charged me 25$ to remachine both the heads and fix the warp/crack

Nice

[cb84capri]

I'm curious how he fixed it, too. I have wondered how well JB Weld or some other epoxy would hold up in a situation like this.

Cale

[wraithracing]

I'm friends with the machinist, he only charged me 25$ to remachine both the heads and fix the warp/crack

Well, that's good to know!

[erratic50]

Post that as a good idea for the guy in the other lane?