Tuesday, July 29, 2008

Bleg: Calling All Mechanics

UPDATE: From comments, it sounds like the original suspicion of the heater hoses or their fittings was closer. These are the hoses for a 1995 Camaro with a 3.4L V6. I'll pull the hoses today and see what I can see. I'm hoping it's an issue with the fittings on the hoses themselves, and not on the heater assembly. I'm imagining a lot more work if that's the case.

I'm trying to get my old Camaro fixed up and sold before school starts. On Friday, I wanted to take the boys to their "camps" and go get some shooting in, since I'd be stuck in nearly-beautiful Springfield for a few hours anyway (City Motto: "Proud Home of Abraham Lincoln's Opium Habit.") Unfortunately, on the way to Springfield, the air in the Camaro grew very warm. Then I noticed that the heat gauge, which reads from 160 to 260 degrees, was pegged at the hot end. That ain't good.

We made it to a service station with a sandwich shop and I called the cavalry and bought the boys lunch so they wouldn't resort to cannibalism (we had over a half-hour to wait.) The engine compartment was full of vapor, but the smell inside the passenger compartment wasn't very strong at all. There was a growing puddle of orange coolant on the ground under the car. After my wife arrived and we took the boys to their stuff, we bought a few gallons of water and drove the Camaro home. It was getting hot by the time we made it home (only about a 10-mile drive, if that) but it made it without adding more water along the way.

I suspected a 'sploded heater core, but my dad pointed out that this should fill the cabin with sweet, sweet coolant fumes. So I suspected a blown attachment where a heater hose connects to the firewall.

So today I needed to jump-start my old truck anyway, and to kill two birds I started the Camaro and let it run. No leaks. I checked, and it was low on water, so I added some, but . . . . still no leaks. Then I looked inside the car--the heat was pegged again. This is making me suspect the water pump is dead, and all the leakage Friday was from the pump's release holes. The problem with that theory is that I was sure the coolant vapor clouds were coming from the rear passenger side of the engine compartment--which is also where the hoses go into the heater core. I have a long history of love-hate with GM water pumps. The hate is paid in full; I expect the love to start any year now. I was too chicken to open up the radiator or a hose with the engine so hot (though the radiator itself didn't feel very hot at all--another reason I think coolant is not circulating.) So I figure tomorrow I'll disconnect a hose and see if the pump is circulating water. If it is, water should shoot out of the hose, even if the thermostat hasn't opened yet, right? I don't think a water pump on this thing would be a HUGE deal, but I thought I'd ask and see if anyone has a better idea.

What's puzzling me here is why I can't induce a leak today? I had more or less pure water running in an engine above 260 degrees. It boiled at around 212 degrees, right? Why isn't it shooting out all over the place?

UPDATE: From comments, it sounds like the original suspicion of the heater hoses or their fittings was closer. These are the hoses for a 1995 Camaro with a 3.4L V6. I'll pull the hoses today and see what I can see. I'm hoping it's an issue with the fittings on the hoses themselves, and not on the heater assembly. I'm imagining a lot more work if that's the case.


Carteach0 said...

Not enough information, and too far away for an accurate diagnosis.
I'll just make observations.

Gauges are not always accurate, and GM's temp sensors are prone to failure once seriously overheated.
DON'T trust the gauge. Use external means to check temp. A digital pyrometer is best, but even an experineced hand will tell a lot.

Water pumps only have a few failure modes, and failing to pump is a RARE one. The impeller would have to erode or a shaft slip/break to do it. Usually when a WP fails it's a seal, and there is a visable leak. On the other hand, a water pump can have an intermittant seal leak. Dump one day, but not again for several weeks.

GM's heater cores and connections are seriously prone to failure. Plastic core tanks and hose connections crack with age and heat. You are correct that a core leak would show inside the vehicle, even if only with a slick and steamed windshield. The hose connections outside the firewall would leak where you noted steam. Try gently manipulating the connectins and see if one doesn't fall apart in your hands.

You did not mention year/engine, but GM uses on most of their vehicles a heater hose connection to the intake manifold that involves a crappy pot metal connector screwed into the intake. It fails with age, and cracks in two. If your vehicle is equipped with that, it can be found by tracing the hose back to the manifold, then manipulating (Tug on it) the connection.

Depending on year/engine, your vehicle may have either a belt driven fan or an electric. Both can fail.

If it has an electric, does it operate? It need not be on all the time, but only when temp is up enough to activate it.
If your vehicle is truly overheated, the fan should be running. If not... you need an experienced tech to diagnose it probably. Motor, relay, sensor, switch, wiring, lots of possibilities.

If an older car with a belt driven fan, you will have a 'fan clutch' that can fail. If it fails disengaged, it will seem the fan free wheels even though the engine is at full temp. It should spin stiffer as temps rise.

You can E-mail me if you like. My address is on my profile. Happy to help if I can.

Anonymous said...

Carteach seems to know what he's talking about and I'm no mechanic (other than shade tree), And I've only owned a couple of GMs in my life...mostly Fords...but I'd mention something that I've had problems with in the past and is easy (and inexpensive) to fix: The thermostat. If it is stuck closed, it will prevent water from circulating. If you have no leaks, but water doesn't seem to be circulating, that seems to me to be a possible culprit that Carteach didn't mention (feel free to correct me if I'm wrong Carteach...did I mention that I'm not a mechanic?).

Carteach0 said...

Yup... thermostat is a real possibility, and I should have mentioned it. Thanks for pointing it out..... it needs to be checked.

As Sailorcurt mentions, failure to flow is often a stuck closed thermostat. Other things can mask that though, like a leaking head gasket :-(

Don Gwinn said...

I considered the thermostat, but something dumped a lot of coolant out inside the engine compartment, so even if that's the root of the problem, there's still something else happening.

It's a '95 Camaro with a 3.4L V6. It's hard to get access to where the hoses meet the firewall from the engine compartment, since it's behind the air-conditioning. Everything on this car is hard to reach. I think it's back to those hoses, though.

The electric fan does run. Yesterday I wasn't really sure what the temp was, but on Friday, that sucker was putting off waves of HEAT.

Thanks, guys. I guess I'll start by finding those connections.

Carteach0 said...


You show a picture of the AC hoses above, NOT heater hoses. Do NOT unfasten the AC hoses... you will not be happy if you do.

Don Gwinn said...

You're right, I just used the picture from the parts site. But I looked up the part as "Heater hose set."

The heater hoses are a combination of rubber hose (from the water pump and manifold) and . . . aluminum? (from there to the rubber hoses that go to the heater core outlets.

I ran the thing in the driveway for almost 45 minutes today. I still couldn't seem to make a leak. I drove it a bit, too, but only around the block a few times. Nothing. I did notice that all the orange residue seems to be up front on the belt accessories, not in the back near the core--but I was sure that was where the steam was coming from on the day it happened. That area is right under the air conditioning--is it possible all that steam was the condensation from the air conditioning getting evaporated by the super-hot engine?

You were also right about the temp sender. It shot up to max as soon as the engine started and stayed there.

So for right now, I just don't know. It has to go to my exhaust guy for a new muffler and maybe cat, and then we'll see.

Brigid said...

It's possible for a thermostat to stick closed, then go open afterwards. After the overheat you had, that Stat is toast anyway. Figure on replacing it, and it may have been your original
problem too.

The system should be pressure checked, as that will show leaks just running the engine will not. Most shops have the equipment to do that.

Also, it's likely that car has a 'fill procedure' to get the cooling system filled properly. A clue will be one or two small brass stems sticking up from the T-stat housing or a cooling pipe adapter near the intake. These are to bleed air from the system,allowing coolent to fill the engine.

Last car I wrestled with was a 67 Cuda 383 S which I stuffed a 440 big block into.

Good luck. . you've got some great advice on here.

Don Gwinn said...

When I was a kid, I had a '77 Bronco that would climb over or through anything (that was the last year of the "real" Bronco that was more like a jeep in concept.)

Unfortunately, it was held together by rust and spraypaint. Doors would fly open on curves. So I bought an '82 Mustang with a dying 255 that someone had once tarted up to look like a GT. The 255/4.2L was the same block as the 302 in the Bronco, so I figured, what could be simpler?

I made it work, but it was more a tribute to a positive attitude born of sheer ignorance than anything else.

Brigid said...

The Cuda was my brothers bought with high miles years later when I was in high school, I sold it back to him recently for top dollar. heh!

That will teach him for giving my Barbi a tatoo with the soldering iron.

Anonymous said...