thermostat and radior hose

[philjherman]

Hey everyone. I recently tool my 2000 Montero in for an inspection. The mechanic said that the thermostat was sticking and causing the upper radiator hose to collapse. This didn't make much sense to me and so I was hoping someone here could help me out.

The truck does not overheat, so I know the thermo is not sticking closed. The temp gage reads below half and I'm not sure how to determine if the thermo is sticking open.

Hoses do feel worn but I do not see it collapsing.

I was thinking of changing out the hoses cause they seem like they could use it and are cheap, I'll do a coolant flush at the same time.

My big questions are:

How can verify if the thermo is sticking?

If I replace the thermo should I go oem or aftermarket? does anyone have experience with the failsafe thermos that fail to open posistion if they fail?

Thanks guys!

 

[SoCalMonty]

Drop the thermo in a pot of water...boil it. Have a meat thermometer or similar in the water with the thermo.

Aftermarket is fine. You can also drill a small hole in the thermo to allow a little water to pass if it doesn't already have one, in case it fails. I've never felt the need, I just see it done occasionally.

 

[philjherman]

Cool thanks for the info. I will pull the thermo and try that. Can anyone verify that OE thermo is 180 degrees? I think this is correct but I can't seem to find the actual spec.

 

[SoCalMonty]

195 or 180 is pretty typical. If it's higher than that, something's amiss.

 

[philjherman]

So I was going to pull my thermo. Found out on this truck it is on the bottom hose not the top hose. So unless I am mistaken I need to drain out all the coolant to pull the thermo. I have a new stant unit and a new upper hose incase I need them.

I don't know how I missed it before but the upper hose is definately collapsing. I noticed it when the truck had been turned off awhile.

So now I have three questions:

What could cause the upper hose to collapse?

Is there anyway to check if the thermo is stuck open without pulling the unit?

Which hose is sending fluid into the engine and which hose is bringing fluid out?

Thanks in advance!

 

[off-roader]

I suspect an old hose is the primary cause. New hoses are able to hold their shape as the coolant cools and contracts.

 

[philjherman]

That's offroader. I will change out that hose and see how it goes from there.

 

[philjherman]

Thanks*** damn you auto correct !!

 

[off-roader]

I believe a bad thermostat is supposed to fail in an open position (so coolant continues to flow) and I can't see how it would cause this problem. That said, replacing it as well as flushing out your cooling system may also be in order if it hasn't been done in a while or you don't know when it was last done.

If you do decide to drain the fluid, there is a pepcock at the bottom of the radiator on the passenger side. Very smart these Mitsu engineers!:ylsmoke:

 

[philjherman]

Hey thanks again offroader and socal Monty (forgot to thank you before!)

I thought it seemed odd that they would say a thermo was causing the issue... Didn't seem right to me.

I read from many Google searches that a bad radiator cap and blockage in the hosing to the overflow tank can also cause these problems. I will look into these as well.

I will keep you all posted with what I find out.

 

[philjherman]

Hey again.

So I looked over everything again and found out the following.

Upper hose stayed collapsed when completely cooled. When I opened the radiator cap it popped back open.

I looked at the coolant overflow and it has a lot more liquid then I ever remember seeing in there.

I checked the lines to the overflow they are all good except I think the hose going in may be bottoming out.

Also it looks like on the overflow cap something may be off. The outer oring looks good but there is a small disc ontop of the hose that goes straight down into the overflow, this disc (part oF the hose) is off center and exposes the hole that goes to the vent on the side of the overflow.

Any have any tips? I am thinking maybe replace the cap. Maybe cutting the hosethat drops sstraight down a bit shorter.

 

[grandpa]

I fixed my collapsed hose issue with a new radiator cap.

 

[philjherman]

I am going to pick one up tonight on my way home from work. I'll let everyone know how it goes. Thanks grandpa!

 

[philjherman]

Alright so I went and got an aftermarket radiator cap and guess what aftermarket caps do not fit the Montero radiator!

So before I ordered an oem one I inspected the original radiator cap. Turns out there was some crud blocking the intake vacuum valve on the radiator.This would explain why the overflow tank was filled. I was able to clean this out and everything is working fine now!

Going to do a full flush and cleaning this weekend to make sure none of that crud is anywhere else. Thanks everyone!

 

[Jay Ayala]

philjherman,

Do you have an update now that its been a while. Did that blockage fix your collapsed radiator hose problem? Is everything okay now?