I mean the radiator. I'll start the engine with the rad. cap off and see fluid flow immediately.

It is RPM related sort of, if I'm cruising the noise isn't there. It isn't until I step on the gas.

It's not a bad sound. Just sounds like a loud exhaust system. I'm hoping to get some snow melting off the truck today to drive it around and take an audio recording for you all to hear.

 

That's so odd... since a hole in the exhaust would also be noticeable when at idle if you just sat in the cab. I'm wondering, do you have bad MPG's as well? If you're not comfortable with the seafoam idea, you can also get 3 feet of hosing and put one end up to your ear. Run the hose along all the exhaust components looking for abnormal "rushing" noises or if you feel any air blowing out. Don't burn yourself.

P.S. about the thermostat, I forgot to mention there is a tiny hole to allow some fluid through, so you might see a trickle of movement but that's it. If it's more than that your thermostat is most definitely gone or broken. Does the truck take a long time to warm up?

 

No in fact my MPGS are great. Been getting over 20 MPG. I have a 86 4x4 pickup 22r.

I forgot about that method with the tubing. I have some new tubing I bought too. Thanks for reminding me.

Yeah so the noise only happens under load. Not just standing still.

I've thought many times that it isn't exhaust noise at all but something rattling at such a high frequency it sounds like exhaust.

This isn't just a little fluid moving. it's a full on movement of fluid. I'm 99% positive my thermostat is stuck open or non-existent like you said.

New one is in the mail though along with a new BVSV. If the sound goes away because of either of those things I'll be thrilled. Not holding my breath though.

 

The truck never warms up. The thermostat gauge always reads cold. SOMETIMES will get just over cold when I drive it for a long time.

I do need to test and make sure my temp sender is working too. But I have a feeling when I put the new thermostat in it'll register.

 

Those senders rarely ever go bad, but it's good to check. However, be ready for overheating issues when you put the thermostat in. Most likely your previous owner took it out to cool down the engine, there's no other reason not to have one in there.

 

Or it's in there and just stuck in the open position.