Overheating and "Popping"

[Robbie]

I have a 1976 Ford F-100 custom with a 360. The truck had been sitting for about 15 years and we decided to get it back up and running. The problem we have seems to be in the cooling system. It overheats and is making a loud banging or popping sound. It originally sounded like something was in the water pump banging around in the impeller. I disassembled the old water pump and did not see any damage to the impeller but replaced the water pump anyways. We found a lot of debris caught in the thermostat. It looked kind of like "oatmeal". We proceeded to replace all of the belts, radiator hoses, heater hoses, thermostat, flushed the system twice and had the radiator cleaned out at a radiator shop. Each flush seemed to get a little more debris out of the system until it finally ran clear. It is still overheating after about 10-15 minutes of running but the loud sound it makes is most disturbing. It sounds as if something is banging abound in the water pump or the head but we don't believe it to be mechanical because the noise continues for about a minute after the motor is turned off. We are really stumped by this. Any ideas or suggestions?

[Lee]

My guess as to the Popping sound is that you are hearing coolant boiling in the engines water jacket.

If you are still over heating after all of the maintenance you have performed my guess is that debris is still circulating and stopping up the small passages in the radiator.

I would continue to flush the system.

Lee

[Robbie]

That was kind of our theory as well. We are hoping that by leaving the flush in for a week or two and driving the vehicle just enough for it to get hot (about 15 minutes at a time), we will clean out the possibly clogged water jackets in the engine. Thank you very much for your input.

[1972hiboy]

Sounds like some old radiator stop leak may have clogged water jackets in the block/heads.

[Robbie]

Sounds like you would agree with continuing to flush to?

[Lee]

Remove the radiator cap and drain a few inches of coolant out. Shine a flashlight in and take a look at the small capillary tubes, are they clogged up?

If they are clogged up with the oatmeal like substance you referenced in the earlier post, try removing the radiator and flip it up-side-down. Then take a garden hose and try and back flush the debris out.

[Busboy]

Stuck or upside down thermostat.

[Robbie]

I also suspected the radiator. Took it to a radiator shop and had it flushed and cleaned. The shop said I now have 95%. Still popping and over heating after reinstall but I am starting to see more debris in the radiator again. This probably confirms more debris is still in the block and possibly clogging water jackets as an earlier post had suggested.

I also suspected the thermostat, so I removed it completely. No change.

I will continue with the long term flush.

Thanks to everyone for the input.

[rwilly]

The heater core was flushed out as well?

Could it be blown head gaskets causing water to get where it shouldn't be?

[Ranchero50]

Post up a pic of the engine. Could be something as simple as the hoses routed incorrectly. Should have the bypass hose for the when the heater control is closed.

What part is getting hot? The radiator? Both hoses? Coolant should flow through the bypass until it warms enough to open the thermostat. Your heater hoses should warm up before the thermostat opens. Does it?

Are you blowing bubbles at the radiator cap upon start up? If so, head gasket. Otherwise I suspect a T-stat related problem.

[Robbie]

Have removed thermostat to eliminate that. No change.
Heater core has also been flushed.
Heater control in cool or warm-No change in popping noise.
Bypass hose is in place between the water pump and the intake manifold.
No bubbles in radiator.
No exhaust gas in radiator.
No water vapor in exhaust after warmed up.
No loss of coolant.
No water in oil.
I have been running the engine with the radiator flush chemical for about 7-8 minutes(Until the popping starts) every other day for the past few days. The radiator water was clear before I started this third flush and now the radiator water looks very dirty. I will be draining and flushing the system with one of those flush kits, that connects to the heater hose, again this weekend and repeat the procedure. Based on what I am seeing, I think the earlier posts were probably correct in that I have water jackets that are very clogged and the continued flushing is going to be the process I am going to have to take. I will send an update as progress continues.

I attempted to attach a video showing the running engine and the noise can be heard, but I don't know how to do that. It could not cut and paste as I would in an email.

Thank you to everyone for your input.

[Ranchero50]

Is the top radiator hose getting hot?

I have a youtube account for videos. Not too hard to set up and post there. Supposedly facebook will allow it as well but I don't go there.

[Robbie]

Just an update on this-
The water in the radiator was very rusty looking this weekend, so I flushed it again until the water coming out was clear and have put in 2 bottles of the flush chemical again. I am planning to run it again several times this week until the popping starts and then turn it off. (I don't want to run it too long and blow up the engine). When the water is rusty again I will repeat the flush out. I think this must be doing some cleaning since the water gets very rusty looking in under a week and the time it takes to start the popping sound is about 1 minute longer than before.

[DragginPanda]

After the flushing, are you running with water? Or did you put anti-freeze back in?

If you're just using water, the rust will come back, especially after the truck sitting so long.

On the long shot side, since there's a constant popping and overheating, even after 95% openness....I'm thinking you have debris in the system. That the lines are getting clogged because of the same debris.

I haven't heard the popping, so I can't tell. I do like throwing the oddball what if though, cause after the obvious, it's all that's left.

[Robbie]

Yes, after flushing, refilling with tap water and the flush chemical again. The instructions on the flush chemical said to do this. Do you think I should be putting antifreeze back in with the flush chemical?

I tired to attach a video that you can hear the popping but could not figure out how to attach it.