I'm having moderate overheating issues with my stock 1970 FJ40. I flushed the system (twice), and when I pulled the lower drain plug, it was bone dry and clogged. I poked, tapped, and chiseled for an hour or so, but I'd have better luck tunneling out of prison with a plastic spork. That stuff is SOLID! I pulled the temperature sensor out to confirm that the upper passages weren't gunked up too, and it's all free and clear (water from garden hose goes straight through to radiator drain).
I should point out that I am not a mechanic, and am learning as I go.
My questions:
1. How important are the lower passages for cooling the engine? It doesn't look to me like there's been any moisture down there since the late 1970s, so it's obviously not a sure engine killer. Not an immediate killer, anyway.
2. How many passages are there? I looked at a forum member's picture with the head removed, and it looks like there are two between each cylinder. If the rear passage is blocked, should I assume they all are?
3. What is the route from that lower drain plug? Does the passage go straight up? The gunk is so solid that it's impossible to tell if I'm scraping the block or ancient, dessicated Stop Leak.
4. Anything else I should be looking at as the culprit? I've ruled out the thermostat and any major obstruction. If coolant is flowing, can I assume all is well with the pump? How much of difference can timing/carb adjustment make? It's running good, but I've tinkered with the carb, and I'm not 100% certain it's adjusted correctly. The overheating issues pre-date my carb tinkering.
I should point out that I am not a mechanic, and am learning as I go.
My questions:
1. How important are the lower passages for cooling the engine? It doesn't look to me like there's been any moisture down there since the late 1970s, so it's obviously not a sure engine killer. Not an immediate killer, anyway.
2. How many passages are there? I looked at a forum member's picture with the head removed, and it looks like there are two between each cylinder. If the rear passage is blocked, should I assume they all are?
3. What is the route from that lower drain plug? Does the passage go straight up? The gunk is so solid that it's impossible to tell if I'm scraping the block or ancient, dessicated Stop Leak.
4. Anything else I should be looking at as the culprit? I've ruled out the thermostat and any major obstruction. If coolant is flowing, can I assume all is well with the pump? How much of difference can timing/carb adjustment make? It's running good, but I've tinkered with the carb, and I'm not 100% certain it's adjusted correctly. The overheating issues pre-date my carb tinkering.
