Blew thermostat, blocked heatercore.. help! :)

[ElmoTheDestroyr]

Hi,

So, I passed someone the other day and the high RPM's apparently blew out my thermostat. The diaphram blew out of it, and subsequently has plugged up my heatercore and I'm getting almost no heat.

It's a 1999 LC 100 V8, I've replaced the thermostat, but I'm at a loss about how to unplug the heater core... Is it possible to reverse flush it somehow and get the pieces back out? lol, PLEASE tell me I don't need to yank the dash and pull the heater core... Did that years ago on another car and I really, really don't want to do that again.

Any advice would be great! Thanks and happy holidays!

 

[Spike555]

How in the hell did that happen? I have never ever heard of that.
I am betting you have a air lock in the heater core, bleed the cooling system of air again.

 

[ElmoTheDestroyr]

How in the hell did that happen? I have never ever heard of that.
I am betting you have a air lock in the heater core, bleed the cooling system of air again.

lol, well, I'm guessing the thermostat diaphram dried out somehow, or just stiffened from lack of use. I bought it from a guy in Vegas and it was basically parked for a couple years... I've put a few hundred miles on it since I got it, but this was the first time I stood on it (to pass someone) ... I think the combination of sitting a long time in addition to 192k miles just killed the thermostat when alot of coolant suddenly rushed through it.

I'll give bleeding it a shot, but it was fine before the thermostat blew, plenty of heat, and knowing there's a thermostat diaphram somewhere in my cooling system, I suspect thats probably why I'm not getting heat... Be cool if its as easy as bleeding the system!

 

[diego355]

Use a garden hose and compressed air to reverse flush the system. I just practiced this with a civic that I got for free with no heat.
Put tons of water thru the heater core for several minutes with constant pressure, then blow it with compressed air. I also did this same process with all the coolant hoses I could find a d the rad.
I got heat after that

 

[LBridges]

What diego355 said. Did it lots of times back when I worked as an independent mechanic.

And unless you did it recently, remember to change out the dreaded T's

 

[bluesquirrel]

Damn...
Make sure to watch for fluid leaking inside the cab, while doing it

 

[2001LC]

Can you post a picture of the old thermostat? Can't see how that would blow apart. If it did come apart, which is doubtful, I'd be concerned with water pump. You did put new OEM thermostat with jiggle valve up, right!

Air in system and temp gauge may look fine or even low (running cool). Cabin heater not blowing hot is the big clue you need to add coolant (most common), have a bad thermostat or a bad water pump.

Bleeding air is easy. Just remove radiator cap after 8 hour cool down, and fill to top of neck. Then make sure reservoir is at low line or a bit above. Repeat each morning until coolant found at top of radiator neck and reservoir holds low line. Check coolant level often, it is the most important system we PM.

Never use tap water in your coolant system, only distilled water. You can use compress air but don't use excess pressure.

I've back-flushed heater lines like this. The heater Tee on LH (DS) is hot side that delivers coolant to cores. I started by blowing air in from RH (PS) and catching on LH (DS). This is very good time to replace heater tees. The below video is a blow engine. Toyota Dealer quoted $13K to replace engine. All because coolant system run low, presumably from blown heater tees. But I doubt you've blockage in heater cores from thermostat blowing apart.

 

[flintknapper]

Hi,

So, I passed someone the other day and the high RPM's apparently blew out my thermostat. The diaphram blew out of it, and subsequently has plugged up my heatercore and I'm getting almost no heat.

It's a 1999 LC 100 V8, I've replaced the thermostat, but I'm at a loss about how to unplug the heater core... Is it possible to reverse flush it somehow and get the pieces back out? lol, PLEASE tell me I don't need to yank the dash and pull the heater core... Did that years ago on another car and I really, really don't want to do that again.

Any advice would be great! Thanks and happy holidays!

If you can help us understand what 'part' of the old thermostat allegedly failed, it would be helpful (diaphragm)?

About the only parts I can think of that are small enough to pass through the system and cause blockage would be parts of the rubber gasket or the jiggle pin. I suppose the wax pellet or piston inside the charge cylinder could do so as well....but I've never seen a T-Stat come apart like that.

It is possible to flush the system at the points '2001LC' pointed out.

 

[Julian Stead]

Why would flooring it affect your thermostat? Unless it was pressurising.

 

[Julian Stead]

Flooring it most probably moved a air lock, the PO might of removed the guts of the thermostat due to overheating.

 

[Spike555]

Why would flooring it affect your thermostat? Unless it was pressurising.

A sudden rush of fast moving coolant through the cooling system.
But what we cannot figure out is how this would happen and what part of the t-stat came part. The whole thing is metal.

 

[Julian Stead]

^^ I can see the thought behind it, but in practice the pump doesn't create anyway near enough flow/movement to create this issue.

 

[ElmoTheDestroyr]

Sorry for the quick reply, I'm running behind on my packing for my vacation starting in the morning so I havent had time to address any replies... Just wanted to say quick... I think it was the sudden rush of coolant when it downshifted from overdrive, to almost redline in 2nd when I went to pass... It somehow removed the rubber gasket/diaphram that seals the thermstat closed... It was just gone.

When I didn't have good heat I thought I'd replace the thermostat, and when I pulled the old one out the rubber was gone... That's all I can tell ya.

It did heat up faster again, but my heat never returned to normal so I'm guessing its clogged in, or near the heatercore...

Anyway, gotta get up and do stuff to get ready, will check the thread next week when I get back, have a good one, thanks for the replies everyone!

 

[flintknapper]

A sudden rush of fast moving coolant through the cooling system.
But what we cannot figure out is how this would happen and what part of the t-stat came part. The whole thing is metal.

No, if OEM it has certain rubber/silicone components (housing gasket and valve seal), but hard to imagine either would deteriorate or become dislodged. Might not have been an OEM T-Stat...however.

 

[2001LC]

Wouldn't surprise me if seal was not used last thermostat replacement.

Worst case seal was not wrapped around thermostat, just placed in cut-out seat of water inlet.

In ether case I would expect to see signs of a coolant leak. Leak would be worst if never installed, than if just improperly installed. Possible FIPG may then have been used to stop the leak.

Pictures of area would be revealing.

 

[Julian Stead]

I still don't buy that reving the engine blew the seal off unless it is pressurising badly. I rev the engine with the radiator cap off when burping, no such surges to be alarmed at. More likely a air lock was moved to the heater core or the waterpump broke and it isn't circulating. Burping this system isn't the easiest as there are no bleed valves and no real height difference between the radiator cap and engine. So have the front of the vehicle as high as you can get it and rev the engine(watch you don't blow your teeth out with the water pressure haha).