Coolant system refresh

I’m in the process of refreshing the coolant system on my 94 4.0 AJ6 coupe. Bought a hose kit from one of the usual suspects, aluminum radiator, fan clutch, thermostat (OEM ouch), rebuilding the fan cowl with rubber flaps since the cardboard flaps are not flapping as I think they should and a heater control valve.

There are two hoses (5/16) which are part of the system which were not included in the hose kit. One runs from the rear of thermostat housing to a 3 way fitting between cylinders 3 and 4. The second one goes from the rear of the throttle body to the same 3 way fitting.

I could not locate these hoses on any of the parts sites. I’m certain fuel line may work but not sure about temp rating. I also found at my FLAPS 5/16 transmission hose which I’m tempted to use.


By the way, I had to remove the throttle body to gain access to the B#####d hose but did not have to remove the intake. The TB shocked me once removed. I’m surprised the car idled at all. I’m going to have to look at the IACV to see if it is in good shape. I can see no light around the TB plate and walls.

I’ll show an after picture once cleaned up. Didn’t somebody here do a catch can to help this issue?


I was able to locate 1/4 heater hose not 5/16 which I thought I needed at NAPA. I spent most of the day cleaning up the throttle body and associated ducting. The big elbow had about 1/3 cup of oil sludge pooled in the bottom and the walls were coated fairly heavily. The PCV hoses are completely caked with oil sludge and are soaking to see if they will clean up otherwise new hoses will be required. Was not planning on the PCV refresh but it is quite necessary. My car has 83K so if yours are in the area, take a look you may want to do some preemptive maintenance.

Pulled the radiator today and was pleasantly surprised to find one leaf in there. No other crud so I assume it’s been out at least once. Note the way the finds are all departing the radiator on the bottom third.

This is on the back side or engine side of radiator.

Have you tried shining a light through that core?

Indeed I have. Found a tag on the radiator which shows a build date of 38-99. I’m assuming week/year so yes, the radiator has been replaced.

There is very little light visible in the bottom third. What is interesting the car never ran hot but over the last couple weeks was running so cool the temp gage never made it to N. I did have a thermostat that was hanging up on the close side which I saw while testing it.

Replacement radiator actually has a drain valve unlike the original.



As you can see in the picture above, the new radiator is much thicker than the stock piece. Great for additional coolant but not great trying to fit the fan cowling.

This is not a plug and play swap. I’m an aircraft structures mechanic and it took all day to trim and fit the cowl to the point where it wouldn’t rub on the aluminum and make the cowl look like belonged there. Very tedious work but fortunately I have metal working tools on hand.

Not sure if other brands of radiators have the same draw back but the Wizard is a very nice piece even if it required additional work.

All the hoses are now changed except for the upper and lower radiator, and a few small bleed hoses. It was quite apparent the hoses have never been changed. I would not want to pay somebody to do a hose change. Can’t imagine doing it on the V12.



If your spoiler tray is still in it really helps to keep the radiator clean, also that bigger cooler gives you some additional capacity, my FASTER JAG’s cooler really helps, and yes changing the hoses on a 94 6.0L will really have saying bad things about British Engineering. I changed out the electric fan with a Spal that helped in traffic and went with silicon flaps from Aircraft Spruce.

The flap material that you used, was it the 3/32x3?

Sorry about the late reply, yes 3/32 . the V-12 shroud only needs two small pieces, it looks like the I-6 needs more.

mine with the Spal fan.

I also used 3/32 neoprene from McMaster. Almost done with the refresh. Having some issues with idle after cleaning the TB.

Thanks for the information

Dzia (Gordon),

I don’t know how old your post is, but I do have a question for you. I have the same year and engine. I finally got enough gumption to attack my seized-up water pump. With little help from my shop manual I did manage to remove the old water pump and indeed the impeller corrosion was horrendous. I also did some hose replacement while I was in there. My problem is this: the two most upper water pump bolts fit through a bracket with two standoffs/spacers located under the thermostat housing block. I can install the spacer on the end of the bracket, but the inner spacer is driving me crazy. There is not enough room under the thermostat block to feed this spacer in between the bracket and the water pump. Do you remember how you fit this spacer (assuming you have replaced your wp)? Do I need to remove the thermostat housing block? I really want to be done with this job!
Randy in Vail, Arizona

I don’t recall the spacers you’re having trouble with, but would a magnet on the end of a stick help?

Hi Kirbert,

Thanks so much for the reply. It seems like you are always here ready to help.
These spacers are a tight fit and need to be forced into place between the bracket and the water pump. The grip of the magnet would just not be powerful enough to push the spacer into place.

What does the bracket hold? Power steering pump?

Randy, my apologies for not responding sooner. I’ve been laid up with some health issues.

I’m sure your complete with your water pump issue by now. I debated replacing mine but elected not to due to it freely spinning and no leakage.