A lot has been written about this but after reading about 20 threads and probably hundreds of posts, I still have a few basic questions.

For context, my deep rumbling noise seems to be due to water pump, fan clutch, or both (thanks Tom R). Given they are both original at 148K miles, they are on borrowed time and due for a change regardless. Getting ready to order parts asap to try to work this over the Thanksgiving weekend (if temps here in NJ rise a little to be able to work outside), but need some clarity. I have the 4.0 GEMS engine.

1. AB, Rover North, BP Utah and others carry fan clutches for the Disco 1 for about $70-130. Are those fine and adequate? or why do I read so much about Chevy Imperials or Haydens 2991, and lots of discussions about more noise, continued running, re-drilling holes, etc.? It seems I can get an OE for similar price than the Hayden (or at most $20-30 more which is OK).

2. I have a thermostat that was installed about 17k miles ago. It is a PEM100990K, which I understand is the 192F (88c). Any reason to change it again when I do the work or is that unecessary? 192 seems to be the original spec t-stat, correct? My truck runs fine with current t-stat.

3. About to buy the generally recommended water pump with brass impeller from BP Utah. I assume that's as good or better than the recommended one from AB (which is $10 more), and better than the $80 ones that RN, AB and others also sell? Any negative experience with that one on a D1?

4. Lots of opinions on gasket sealant for water pump install . . . is permatex ultra black RTV adequate? I have some leftover from recent t-case repairs. I also have blue hylomar.

Thanks in advance.

 

OK,

The stock clutch is fine unless you run hot in summer then the s10 clutch seems better with s10 fan, cut 1" off each blade

Or s10 clutch with rover fan just oversize the bolt holes in fan as the mount slight different

Stock wp is fine with gasket they include, can glue the gasket to pump, iirc the bolts are a pain as sort of glued in with sealer?

Might as well swap to a 180* stat while in there part # in tech section

Need the tool to remove fan

Order from ab for our area usually shows next day if you order in morning nothing against other guys an is just close for us, unless you want to wait, I also find that others are a little cheaper till you add the shipping from farther away

Check hoses might want to do em while in there and flush engine good while apart unless recently done, new antifreeze

 

IMHO, unless you are trying to make something work in a pinch or have a heavily modded rig, OEM is best 95% of the time. i run the chevy S10 clutch but plan on going back to an OEM one once the weather warms up. i don't feel like the chevy standard duty one "locks" enough, and the HD one is locked up way too much.

the OEM stat is what you want to use. UK stats are FULLY OPEN at the listed temp, while US stats (stant, motorad etc) START opening at the listed temp. that is why people recommend the 180F. i'm running an OEM 88C stat and can watch it open and close through my water temp gauge on hot days.

 

I am switching to electric fans, but I currently run rover fan on s10 clutch from autozone , they must only sell the HD one cause I think it runs all the time, but with that and 180* stat I run constant 177* on ug, iirc not much worse with summer heat and both a/c on

But I also push all the extra weight on my rig so...

 

the HD fan i bought at first was always locked up so tightly i was afraid to push the gas pedal.

 

Thanks for the guidance. I ended up buying an OEM clutch which I found on sale for $75, the ATX water pump, and the hose kit from AB which inlcudes the genuine 88c stat.
Also got a new belt, permatex thread sealant for the long WP bolts and high tack for the gaskets.
I assume any 50/50 green coolant will work so will pickup locally.
Will try to do all the work this coming weekend.

 

Yup greens fine, flush good ESP heater core

 

depending on where you are, it can be a PITA to find real "green" coolant. there are debates upon debates about HOAT/Dexcool/whatever is used in the all makes/all models stuff. I ended up buying a case of Zerex green pre-mix through amazon bc my water sucks and I have amazon prime so it was cheaper than buying from auto zone anyway.

 

Should be all set, just remember the thermostat housing and front cover bolts can be a pita and snap.... Get the engine nice and warm before you remove them, take it for a drive to get it up to operating temp and you shouldn't have a problem keeping your hands warm and your bolts turning.....

 

Thanks. I hadn't heard the tip on warming the engine before attempting the bolts, so very helpful, especially as we expect snow and cold weather this weekend.
Regarding real green coolant, I just got premixed ethylene glycol based coolant at local Pep Boys (their Proline brand). .hope that works fine.
I also learned a tip on an AB tech video about draining 85-90% of the coolant through the lower right wp bolt before removing the bottom hose, for a less messy process. Then I'll flush radiator and engine, install new hoses, new t-stat, new wp, reassemble everything and refill/bleed per Rave/Haynes instructions.
Newbie question: I assume the gasket is placed with fuzzier side facing the engine? (one side seems a bit fuzzy and one is plain with writing on it).