r/SuzukiSamurai

My heater barley blows any heat, I can hear the fan working, and the heater control valve works. Wondering if there is anything else specifically I should check before tearing it apart

Hey guys, a while ago I got my santaja sj410 engine's rebuild and after fixing some electrical problems something else showed up: temperature fluctuations with the pedal pressed. To be clear, this is not the engine's temperature going to the top and staying there, it's raising to around 2/3s of the scale when pushing the engine hard-ish and coming back to normal (1/3) after some time.

Things I ruled out:

1. faulty thermostat (both I tried are opening and closing at the correct temperatures),
2. faulty sender (there are actual fluctuations near the sender and in the oil filter, I tested it with a thermometer),
3. problem in the head (there is no mix of oil and water), problem in the cooling circuit itself (no leaks).

What I couldn't rule out:

1. something INSIDE the cooling circuit, even though I purged it again and again (the level of coolant raises and plunges quickly in the expansion bottle),
2. the radiator is too big for the car/newly installed water pump (I installed it before engine rebuild and it actually stopped the car from overheating when idling, so I don't see it making any sense unless the water pump that was there was stronger than the one they rebuild it with, which I doubt)
3. The final carb tuning was badly done and it's too rich when revving, which would also explain some (burned) gasoline smell and higher than expected emissions when revving.

Have any of you had a similar problem before? What of the 3 possible causes do you find most likely? I do know how to tune carbs but I'm more used to smaller/simpler engines, so I don't want to mess with it unless I'm positively sure that that's the cause.

Thank you!

You all may all have seen my other post about my AC install, just know all of my testing here is with the AC off.

Ive done a lot of work to my 87' tintop, it was having some bad oil leaking issues, and heat issues, so I decided to really go through it over the past few months.

Before I started working on it, I had no issues reaching 70mph flat, and was able to climb a hill near my house and maintain 55mph in 5th uphill. Now it cannot, it can barely do 55mph flat and level.

Things ive done;

New timing belt, cam and crank seal

New water pump and oil pump gasket

Distributor housing o-ring and distributor o-ring

Larger aluminum radiator and electric fan

GM 12si 100amp alternator

Rotated "improperly" installed Weber carb

Relocated PCV valve for carb clearance

ReGeared transfer case, 4.9

New clutch and flywheel

New U-joints, all

Tried various timing, 8btdc, 10, 12, and now 15

Verified mechanical advance is functioning

Added fuel pressure gauge, and experimented with an electric pump, no change.

I have a few things to try this weekend, new plugs, check vacuum advance functionality, and i have to replace the valve cover gasket, so I can check the valve lash while the cover is off. I banged up the exhaust quite i bit when pulling the transmission, so I also have an exhaust leak now, going to replace the gasket and donut as well.

Any other things I should try/check?

Thanks all!