Overheating and no power discovery 3.9 V8

Hey guys having a couple issues. 1993 Honda Crossroad (Landrover discovery) 3.9 V8

Overheating problem started just recently, will slowly creep up even just idling but also while driving around. I've had it just a little over 3/4's on the gauge and at this point the top radiator hose was at around 100 degrees celcius at the thermostat end. I've taken the thermostat out and it opens as it should in pot of water so have put that back in. There's only about an 8degree differential between the top of the radiator and the bottom so I don't suspect there is a blockage.

I've attempted to bleed off any air in the cooling system but not sure if i'm getting it all out. Heater only gets warm not hot. I've had the bung off the metal coolant line heading into the heater while running the engine and coolant comes out but in surges with a few seconds in between any water coming out. Is this normal or could there be a blockage in the heater?

There's ample coolant in the system. Pretty sure the water pump is pumping. Wondering about the viscous fan at this point. It spins freely by hand with the engine off, but this seems correct to me? It should only couple with the belt driven end if the engine is hot....actually that's something I haven't check if it freewheels while the engine is hot. But the fan still spins with good air movement while the engine is running.

Power issue I think has something to do with the distributor. I took the vacuum advance unit out of the distributor to allow better access to the thermostat housing bolts. After putting this back in the power is just non existent. Foot to the floor and nothing. Does this have to go back in a particular way? I have tried blowing and sucking on the hose at the inlet manifold end and there doesn't seem to be much resistance at all and there's no movement of that arm inside the distributor. Wondering if the diaphragm somehow got damaged when removing it.

Any help would be appreciated!

Thanks

Hi, the best would be as first move to get a sniff test on it to rule out a combustion leak cos that not hot enough heater is suspect... if the test is negative plug in a tester to see if there's not some engine coolant temp sensor fault logged eventually read live data and compare sensor inputs with measured temperature, the fact that you have 100*C real coolant temp but the gauge is above half can be a bad reading from the coolant temp sensor cos the gauge is supposed to leave the middle upwards only at 120*C and at that point the management cuts fuelling for overheat prevention that's why it doesnt have power

That's real interesting bout not supposed to leave half way until 120*C. It was continuously climbing and saw it get up to 110*C as well. I think it would've gone higher. I was a little concerned how high to let it get so i shut it off. What's the max temp before damage is going to start happening?

As for the power i'm not convinced that's the reason because it's still lacking even when the gauge is below half. Struggled to reverse up my driveway (not steep at all) just before and that was at 1/4 gauge. If this vacuum advance unit is at fault can I advance the ignition timing by adjusting the distributor to compensate for it? I really wanna use the Disco for a little short drive to go camping in 5 days so I'll settle for a temporary fix at the moment. As it is it's unusable.

AAAha, sorry, i missed the MY of the engine ... forget what i said about the gauge then, though better compare the sensor readings with the real temp if you can, ... for any engine 110*C would be the max limit before getting dangerous

I took the vacuum advance unit apart and the diaphragm was very brittle and had torn. I'm wondering if this was also the cause behind the overheating as it may have been on the way out but not completely ****ed and messing up the ignition timing. Now it's rooted beyond repair. I think just a light knock when i took it off and set it down might have been enough to damage it further, it's that brittle. Have to wait for a new one to get in then I'll find out more I guess.

Replaced the vacuum advance unit and that's fixed the power problem, also the timing was waaaaaay out. Set to 7~ BTDC. Still having overheating problems though, but theyre inconsistent. Sometimes it's overheating idling, sometimes not. It is overheating on the open road. The viscous fan spins freely when the engine is hot so I imagine that's ****ed. But that shouldn't matter on the open road I would've thought with the amount of airflow that would be going through the radiator?

Using a digital temperature gun the top radiator hose is at 90C while the LH radiator side is getting to 100C. I'm not sure which is the more reliable reading to go off.

Did a headgasket check and that seems good. Differential between radiator sides was 15-20 degreesC. I was measuring that wrong before. Thinking it might be worth pulling the radiator and giving it a good clean out.

Also it has an exhaust leak at the manifold on the engine, could this affect my temperature in any meaningful way?

All the air in the cooling system has been bled out.

When u say overheating is it boiling over?
Do u know that one side of the radiator housing is the engine oil cooler, if the engine is hot the fan will spin with some resistance depending on the temp of the rad.
Does the fan spin freely when cold ie. first thing after standing over night? as it shouldn't.
A blown exhaust gasket will not affect the engine temperature, the gasket between the downpipe and the manifold is a known weak spot if you have an auto.

Did you ever use the tester to inflate the bags with it to see how they respond?, if you use only the inflate/deflate command with the arrows it will not loose calibration ... this would be good to rule out the possibility that the valves are connected the other way around(RH valve to to LH bag and vice-versa) cos that would mess up the wholr SLS behaviour without affecting the actual horizontal self levelling