Toyota Soarer V8 Hydraulic fan leaking. May convert to electric fans. (Lexus SC400).

The 1UZFE EGR Delete Kit is available for sale here.


Hi guys, I have an issue.

The 1UZ Soarer hydro fan seems to be leaking from somewhere...

It appears the hose clamps may be bad on the pump outlets as that's where the gunk is but I cannot see the problem properly so the car is booked in on the 11th to be checked. I suspect a failed pump (probably the 30 year old seal) however.

I can't find a pre owned pump anywhere at a reasonable price, so I am thinking about converting to electric fans if I can't find a cheap pump, motor, or whatever the issue may be when I find out.

I've read various threads on this forum about electric fans but it seems after a while a few people had their pumps blow up, such as forum member "Jibbby". It would appear if you block the pump outlets and keep running the pump's pulley with fluid inside it will blow.

I have a couple of questions:

Can I bypass the fan pump pulley totally and just run a shorter belt? The fan pump won't be used with the electric fan setup, and it is not moving, so won't heat up and blow, right? Or am I missing something? Are there any ill effects to this?

Here is a diagram of what I may plan to do with the fan pump pulley:


2. Soarer hydraulic fan airflow rate is said to be 4400CFM - A 16 inch electric fan puts out under 2000CFM. What minimum CFM is actually required to keep the V8 cool in 30 degree celsius weather? Some say a v8 requires 2500CFM, others say 3500CFM, etc.

  • The hydraulic system is no doubt overbuilt and performs way above expectation for this 4.0L engine.
  • In an emergency anything is better than nothing, so I am looking at a 16 inch fan or two 14 inch fans.
  • CFM numbers are pretty useless online - cannot be trusted.
  • 95% of electric fan specs are lies.
  • I expect two 14 inch fans to pull about 2000CFM or so in real life.
  • On top of this, some people (possibly shills) are claiming their $200+ 16 inch fan which probably pulls 1800CFM max is fine for the 1uz v8.
Update: It appears the hose clamps are leaking on the pump upon closer inspection but it could still just be fluid from when it was spraying out from elsewhere...

Update: It appears the bolt where hose joins to fan is leaky, as well as clamp on pump-side. Will try tighten it and see how it goes. Seems pretty tight already though.

If anyone could help out with this dilemma, I'd appreciate it.

Last edited:
I think you will find the belt wrap on the crank pulley may not be enough.

It could lead to belt slip when the air is on, turning a corner and the alternator working a bit hard such as late at night in the wet.

The perfect time for that to happen. it won't stop the engine or car but will sound horrible.

From memory the hoses bolt on with a Banjo bolt and use copper washers to seal the joint. Try replacing the washers as they are really a "one use" item

another option is to purchase a fan bracket (they are cheap in the States) and pulley and swap it out.

I run a twin fan assembly off a Ford big 6 that works a teat.
Hey Zuffen, thanks for the reply.

I went to the mechanic and he said "I don't know what is leaking, the pump or just the hose, blahblah, it will cost lots to remove it to check".

The cost of this, is the same cost of just converting to electric. I'm thinking I will have to go electric.

Curious in regards to the washers - do you have a part number or know which type to get?
I just did a major service so everything was undone (and now everything is leaking!).

Do you have the replacement fan bracket pulley number, or a link to one so I know what I'm looking for at all?

Also turns out my steering rack has a small leak and boot is torn too, another glorious present I received after getting the car back from the mechanics.

Do you know of anyone selling one here?

Google 1UZ fan bracket and they will turn up. If in the USA they are readily available.

The pulley that goes on the idler is available from Toyota.
I used a fan bracket for an early LS400 90-94 pn T-150. It was on ebay and was sourced by NPW in AU. The pulley is also available. I replaced the entire radiator, catch tank and fan assembly. It wasn't cheap - I used a 66836 Derale dual fan w controller. I understand you can use a GM truck dual fan setup as well if you hit a salvage yard. I had to trim about 1" off the battery tray in the corner by the radiator (see pic 2). The fan size is 17"x25.5" 4000 cfm.