1HD-T Coolant Flush

[Cruisin']

Its time to flush the coolant in my 81 for the first time (for me, hopefully not for the truck). I've read the FAQ in the 80 section regarding this procedure, but of course this is for the gasser. Any suggestions on doing this for the diesel, and most importantly, where is the coolant drain on the engine itself? I've searched, but I have not found

I plan to drain the coolant while hot, then fill everything with fresh water to flush the system, then drain again and refill with coolant and de-ionized water.

That's my plan, now fellow mudders, please do what you do best and educate me!

Jason

 

[Towpack]

Looking at the manual the engine drain cock is either on or just below the oil cooler.

Do not drain the engine while it is hot unless you're going to refill it with very hot water or wait for it to cool down first.Hot engine + cold water = cracked block/head.I've seen it happen.Better to drain while cold and get a garden hose in there and back flush the system,particularly the rad and the heater matrix.To do this right require stat removal of course but you're probably sticking a new one in there anyway?You'll be amazed at the s***e that can come out of what appears to be a clean system with good coolant colour.
There are,of course, numerous proprietry flush additives available but I've never used them myself.

 

[Tapage]

keep in mind when you rin a cold engine you are flushing only the engine " cooland " coz the t-stat it's closed .. but the water pump it's moving anycase .. so after that you will need to flush apart the rad ..

 

[Cruisin']

Do not drain the engine while it is hot unless you're going to refill it with very hot water or wait for it to cool down first.Hot engine + cold water = cracked block/head.I've seen it happen.Better to drain while cold and get a garden hose in there and back flush the system,particularly the rad and the heater matrix.To do this right require stat removal of course but you're probably sticking a new one in there anyway?You'll be amazed at the ****e that can come out of what appears to be a clean system with good coolant colour.
There are,of course, numerous proprietry flush additives available but I've never used them myself.

Thanks for setting me straight. Not sure why I didn't think the hot/cold thing through

I'll be doing a pretty thorough flush, since my system is not what you would call clean with good coolant colour. I don't have the history of the truck, so this is just part of baselining.

 

[Greg_B]

If you're going to do the cold flush, then take the t-stat out. Probably want to baseline with a new t-stat and o-ring anyway.

16346-66020 for the o-ring
90916-03089 for the t-stat

hth's

gb

 

[Cruisin']

Thanks for the part #s Greg, I'll add them to my running list. I pick up the parts tomorrow.

Jason

 

[Cruisin']

If I'm pulling the t-stat anyways, do I still need to drain the block at the plug, or is the lower hose low enough to get most of the coolant out?

 

[canucksafari]

Take the block plug out as well and make sure you flush it well. When I did mine a couple months after the importer said he had done it there was still a bit of crud coming out from the block plug. I don't think the importer did a flush, like he claimed. He just disconnected the lower rad hose and then refilled.

 

[jinzuke]

block plug

block plug ?


where is this block plug located. I know its on the block but where.

 

[DBWood]

BUMP!

So, where is this block drain? And, if I don't have access to a new T-Stat, what would you do?
I am thinking if you guys help me find the block drain, and I drain it there, and the rad draincock. Then refill the rad, start the engine and let it get hot until the T-Stat opens and top up like that?

Any help is appreciated!

Doug

 

[Falco80]

Doug, here is on my old HDJ80. This is the 1HD-FT, but i assume the 1HD-T is the same. It was located just above the oil pressure sender and had a neat little spout that i could attach a tube to, making it a clean job.

 

[johnnyp34]

rookie question but where do you access the t-stat on the 1hd-t (91 hdj80)?

 

[roscoFJ73]

rookie question but where do you access the t-stat on the 1hd-t (91 hdj80)?

Remove the metal pipe from the engine block that the lower radiator hose attaches to and you will see the t/stat. Makes sure it goes back in the right way.

 

[1HDTRocinante]

I am doing a coolant flush for the first time on my 1994 HDJ81 (1HD-T) and I cannot find the engine block drain anywhere. Any help is appreciated. The importer put in GREEN coolant … so I want to clear it all out before I put in the correct coolant.

 

[rick_d]

Cleaning out rusty water passages

Hey! So I am getting ready to swap out the water pump on my 1HZ and thought this would be a perfect time to really clean out the cooling system. I back flushed the system and got a lot of crud out (even two heater hose pieces from somewhere! I'm surprised a boot didn't come out!). I did...

forum.ih8mud.com

While running, run a clear bypass hose from heater angled fitting on left side above starter to right side long tube that feed the front system (see behind turbo).

Boil water to mix w oxalic acid, neutralize with baking soda in boiled water.

Tell us if "clear" or dirt mung color while flushing.