HELP!! No Heat From Heaters! Isuzu Mu, Driving me mad!

[32theworld]

Hi, so i've got a 2.8T isuzu mu, since ownership heaters worked fine, temp gauge would only sit quarter way but it didn't bother me.. everything worked well! I replaced thermostat at this point for peace of mind (figured maybe it had been removed or slightly old). So thermo is brand spanking new. 3 weeks ago I got a diesel leak from the inside cap of diesel pump, my mate and I removed intake, all water lines and everything to get to it. It worked, we fixed the leak and its great.
BUT now the damn heaters wont work haha, I've checked for pics of my lines to make sure they are in the correct order and they are from what I can see. The heaters DO work but Only when going 100kmh for 10 minutes or more.. I can drive around town all day at 50kmh and its dead cold. Temp gauge also sits at half way now (Which doesn't bother me, its no where near over heating), uses no water or anything at all. running great, just heaters.. So if I go 100kmh and then arrive back in town for example after about 10 minutes of 50kmh around town driving the heater will slowly get colder haha..

Any ideas at all?? Ive also tried bleeding the system the usual way, but it took 40 mins to get to temp at 3000rpm with choke on.. lol not even kidding! and the heaters started working after that? but it took 40 mins. please help, any help is much appreciated, ive asked everyone I normally ask for help and same answers generally which ive checked it all..

Thanks very much guys

[geeves]

Try disconecting the heater lines and run a hose through the heater core. It might be blocked. Could also be a air lock. If running the hose through doesnt help try reversing the 2 hoses to the heater

[32theworld]

Where do I run the hose to?? any pics? and thats what I was thinking.. A air lock, but if im struggling to bleed the system how do I remove this air lock?? haha cheers for reply man

[geeves]

After filling running the engine with the heater on hot should bleed it. Swapping the 2 lines to the heater at the most conveniant point might fix it but those hoses line up correctly pretty well unless they are non original. My money is on flushing the heater core

[32theworld]

Could heater core get blocked after doing one job you reckon? as the morning they worked then we did diesel leak and afternoon test drive no heaters haha

[32theworld]

[32theworld]

[32theworld]

So have just drained all coolant and flushed with hose, then proceeded to bleed system for a hour.. took forever to get to temp, barely any bubbles came out and heaters were not working even though at operating temp. I checked the heater hoses and this is what the outcome is. red is warm/hot, blue is cold.. so the pipe with two colours go's from warm to cold, any help is much appreciated thanks !!

[32theworld]

[32theworld]

Have just finished flushing the heater core, bit of rusty water but nothing major.. took for a drive, no change, so swapped around heater hoses on firewall, same deal.. no change..

[32theworld]

Fixed it!! The two hoses right next to each other up above were simply around the wrong way, crisp warm air now! Thanks for the help and hopefully this post can help out others in the future!!

[geeves]

that saves me posting photos Ive just taken of mine.
All good