loud thumping in coolant system

[kyled07440]

Hey guys.I need some expert help, I'm stumped.so my problem is when the truck is running and up to temp I get a loud thumping from my coolant system.I can actually feel it in the floor board.I had this issue a few months ago.I didn't know what it was at first.I happened to have the hood up one day when it started happening.I noticed it was clicking in the heater hose.I back flushed the entire system and all was good.until a few days ago.now it's back.I'm pretty sure from what I've read that it's the coolant boiling.but there is brand new coolant in it now...also my temp does fluctuate quite a bit.I think it's just the thermostat.but what do you guys think? Thanks in advance

 

[Anime]

Did you follow the procedure to purge the air out of the system when you filled it back up with coolant?

If you don't purge the air out by running the engine at idle up to operating temp with the cap half on, then letting it cool, topping it off, then doing it once more, and topping it off again, you can get air in the system that cause issues. This can manifest itself as a loud noise from the pressure that builds up, and usually the coolant under pressure comes out the overflow reservoir tank and makes a lot of loud gurgling and bubbling noises as it overflows and the pressure is released from the system.

Air in the system can also keep the coolant away from the thermostat and cause the engine to overheat as the thermostat won't open and will melt shut when the engine overheats.

If you purged the air and the thermostat is good and the temp stays in the NORMAL range, then it might just be a rattling water pump that is going out.

Otherwise the thumping might be something else, if the temp stays in range, the coolant is topped off, and nothing really points to the cooling system.

 

[kyled07440]

When I added coolant I used that special funnel thing that keeps air out when filling.after I flushed it, it stayed nice and quiet for at least a month.I also replaced the water pump a few months back.and my temp does kinda stay in the normal range.but like I said,it will get to temp then drop quickly to cold, then go back to temp and again rapidly drop.

 

[cogs]

the thermostat is working, since the temp rises, then the tstat opens, which makes it read cooler then.

*slowly* turn up the heat temp, and see if it changes in any way. (if not slowly, you may bust the plastic valve near the firewall).

 

[kyled07440]

I know the stat is working, but I think it's screwed up.the temp will go up to the m or so, then falls to the n or a little below.seems a little dramatic to me.I expect a drop when it opens but not like that.and it's been like 10 degrees out all week, so my hat has been on full blast.

 

[burgundy1994xlt]

Had the same issue when I first got my 94 xlt. Mine needed the air bled out of the cooling system. Typical on these.

 

[Southern_Pride]

Make sure the overflow bottle is full as well.

 

[Turdle]

You still need to burp out the air. The radiator cap is lower than the heater core. When the coolant is drained out, air goes in.

A fancy funnel doesn't make any sense--as any air introduced into the radiator will go to the top of the radiator and be pushed out by the adding of coolant.

Get the front end of your truck jacked up about a foot, then refill the coolant with your heater turned on to full heat.

Warm up truck with heater running, let cool, add coolant, repeat.

The thumping is steam pressure. Either you are low on coolant, the thermostat is closed, or, you have a blown head gasket.

 

[1ralphnelson11]

1991 explorer xl, 4.0 4x4.. Just changed the w water pump today, along with the serpentine belt, upper radiator hose, heater/waterpump hose, and flushed out the radiator and coolant reservoir/ wiper fluid tank while I had them off. Drove to work about 7 miles, ran fine. No leaks or noises. That was at 4 pm yesterday. At 6 am, started the explorer, engine is making a rapid ticking or clicking sound at idle with throttle or driving. It doesn't overheat or blow smoke. Any ideas, tips?? Need help ASAP!! thanks guys...

 

[2stroke]

You should start a new thread to get your question answered properly. There are two common problems that sound like a tick. knocking or lugging and valve train noise. Since yours does it constantly, I'm thinking valve train noise. Someone recently posted a similar problem. Check the link below, and see if the video sounds like your problem. If you have more questions, post a new thread.

http://www.explorerforum.com/forums/showthread.php?t=421170