Your pump would leak around the gasket or out of the weep hole on the bottom of the pump. There is a hose or two back there, I've had to replace the 90* hose from the heater and another one that was lower, forget exactly where.

Doing all the hoses on an aging engine is always a good idea, and is good insurance, even when they're not leaking. My suggestion is get the cooling system under control first, and then tackle the idle.

Eddy's suggestion of head bolts is not for the idle, but purely because of the heat you may not have even noticed, when the coolant was low and the gauge sender was above the waterline. You certainly want to keep that head clamped on good.

Here's the factory service manual link, though you can find it in the mentioned stickied thread at the top of the list...
http://www.mitsubishilinks.com/fsm/montero_fsm_1989_enginechassisbody.zip

Phil

Hi guys,

Just removed all the hoses and wow that was A LOT of work. Not hard but as you said they were hard to get to. None of them seemed broken though.

Do you know where the thermometer sits on the car for the coolant? Is it behind the thermostat? I did remove the thermostat just in case.

I should also point out this: When I removed the hoses on the back, coolant came out. When I removed the lower radiator hose, coolant came out too. So, how is it possible that it overheated over when there is coolant in the system? Could a blocked thermostat be the problem? The thermostat moves when I push it so it seems strange why it overheated earlier.

Karl, the hottest part of the system is the head, which is also the highest point, so if the coolant level is low, part of the water jacket is not covered with coolant, and this does not shed heat to the coolant. It gets a steam pocket there, and steam does not absorb heat worth a damn. It also does not open the thermostat worth a damn, so what little coolant is in there does not circulate.

Removing the thermostat is a bandaid, and will not solve your problem.

Oh and one more thing.. Should I replace the water pump while I'm at it too?

it's easy to replace anytime so it's your choice. Just dont buy a cheap junker one, will probably fail before the old one.

I finished replacing all the hoses today but as I was clamping the last one to the firewall the clamp screw popped off and went hiding somewhere in the engine bay. Since it was raining on me and I had been standing in an awkward position for two hours I stormed off furiously, so TBC tomorrow.

I have been wondering what caused the leak and overheat, and noticed a few things:

The overflow canister is constantly empty. I used to fill it up between the 'low' and 'high' mark but the coolant disappears within hours.

Regarding the overheating: Could a faulty/blocked thermostat cause excessive pressure to build up in the system and eventually lead the heater/bypass hoses to leak? Would that show up on the thermometer? AND: Could a faulty water pump lead to the same issues?

I am still unsure why my system kept leaking and overheating, and I want to believe it has something to do with the overflow canister since the pressure should have pushed some coolant into it.

EDIT: Regarding torquing up head bolts, do I need to remove the rocker cover to get to those?

I'm pretty sure you have a blown head gasket. The coolant loss is indicative.

Yes, you have to remove the valve cover to get at the head bolts, and the bolts take a 10mm allen socket.

Blown head gasket is more than I can handle, so if that is the case I will probably get rid of this car once and for all and buy a motorcycle. <img src="/forums/images/graemlins/angry.gif" alt="" /> I don't think it is however because the coolant is/(was when drained) as clear and green as can be. The oil is also pretty much in perfect condition. If the seal was broken to the extent the car broke down and hoses sprung leak, shouldn't there be clues in the fluids?

I just bolted the thermostat housing back on and it cracked on me. Is there a fool proof way of getting it back on without spending money on a torque wrench? It is really hard aligning the thermostat since there are no edges it can grip and the housing ended up squeezing one side more than the other and it cracked. My gasket has glue on one side and attached to the block; should I apply glue to the other connecting with the housing to prevent the need for over-torquing it?

Thanks for ALL the help so far, I'll be sure to post pictures of a happy temp gauge once this mess has been taken care of. <img src="/forums/images/graemlins/cheers.gif" alt="" />

No.