Birty Dastards Jeep Club

Tech Forum => Workshop => Topic started by: prozac on April 05, 2007, 11:28:47 AM

Title: Transmission cooler
Post by: prozac on April 05, 2007, 11:28:47 AM: I have a 2001 4.0L Cherokee XJ Auto. I tow a van and carry mountain bikes at the same time.
We caravan in the Peak district and use the A515 Ashbourne to Buxton road regularly. Those that know it, know the drag up out of Ashbourne is pretty steep. I'm ok on that. The climb up out of Fenny Bentley is a different sort of hill, long and still quite steep, we seemed to struggle more than I would have expected near the top. Every hill there after seemed a struggle for the Jeep. It seemed a bit asthmatic, a bit gutless.
Without the van, the Jeep pulls well.

Do I need a transmission cooler or should I be looking elsewhere, or is there nothing wrong.

Cheers
Prozac
Title: Re: Transmission cooler
Post by: tim_aka_tim on April 05, 2007, 11:42:26 AM: Quote from: "prozac"
Do I need a transmission cooler

You already have one If you wanna pull up hills, towing caravans, then you need a turbo diesel.
Title:
Post by: Mike Pavelin on April 05, 2007, 12:42:15 PM: I find staying in nice hotels saves wear and tear on the Jeep and doesn't annoy other road users as much
Title:
Post by: Dave69 on April 05, 2007, 09:37:24 PM: your transmission cooler is located in the radiator itself ( the left hand side viewed from the front). It may not look alot but it is a very effective unit.
Title:
Post by: prozac on April 05, 2007, 09:49:23 PM: So I don't need an extra transmission cooler...... what else could cause the .....er....... apathy?
Title:
Post by: Dingo on April 06, 2007, 09:23:12 AM: Has you got big tyres on? That climb out of fenny bently is a hard one, I know it don't look much and from there on it's just as hard, try it in a lorry and you'll know why you're struggling. Oh and the climb past The offroad quarry before tissington is the worst one, used to have me right down the box in the ERF.
Title:
Post by: prozac on April 06, 2007, 09:42:35 AM: It is a tough old road!! I've got road tyres on tbh.

On the same trip, and it happened again yesterday, I got an odd vibration EXACTLY like driving over rumble strip, only I wasn't driving over rumble strip And it stopped as soon as I took my foot off the throttle.
I was in 2 wheel drive only.

I've booked my car in for a 30,000 mile service in a week as it's just done 90k and I'm not sure when the transmission fluids were last changed.
Title:
Post by: Dingo on April 06, 2007, 10:09:26 AM: Check your prop shaft just in case.
Title:
Post by: Mike Pavelin on April 06, 2007, 03:41:33 PM: Sounds like you may have a plug or HT lead breaking down.
Title:
Post by: prozac on April 06, 2007, 04:00:22 PM: Does it have HT leads? I thought there was a little coil for each plug.
Title:
Post by: Mike Pavelin on April 06, 2007, 07:14:37 PM: Hmmm.. 2001 Cherokee. Didn't notice that

Check the plugs though.

Come to think of it. I have a mate with a 2001 TJ that has coil on plug ignition. It used to run fine unless it worked hard and got really hot, in his case while offroading. It would then drop onto 4 cylinders. Dealerships changed the coil packs twice with no success.
In the end I stopped it happening by fitting a stainless heat shield between the crank sensor and the exhaust manifold. Hasn't done it since.
Title:
Post by: prozac on April 06, 2007, 08:50:12 PM: Mike, as ever, you're a feckin genius!!!! I'm sure off-road may be similar to pulling a 1400kg caravan up a long hill.... it may make the engine a tad hot.

I said to the wife I didn't think it was running on all cylinders........ as I'm a thick sh1t ........ is this heat shield buyable or do I have to make it? and where does it fit?

Thanks once again, this sounds right on target.....

Martin
Title:
Post by: Dave69 on April 06, 2007, 09:29:47 PM: the heat shield is something you can knock up yourself, normally they are 1 to 2mm thick so to add a bit of substance so it doesn't bend too easily.
these are normally bolted in place but you could bend and shape an individual shield for each spark plug. Most people bine these as they just can't be arsed to refit them as they dont seem to do anything
Title:
Post by: prozac on April 06, 2007, 11:17:53 PM: I'll have to pop the bonnet tomorrow and see if I can figure out what I'm shielding from heat..... like I said, I'm a thick sh1t :? :(
Title:
Post by: Mike Pavelin on April 07, 2007, 08:03:37 AM: Behind the exhaust manifold at about the 1 o'clock position on the bellhousing you'll see the crank position sensor attached with 2 small bolts. At low speeds and heavy loads this can get very hot and begin to malfunction. It only appears to happen on some
late 4.0s with the distributorless coil on plug ignition.

It's not an official fix but no-one else could figure what was wrong with the Jeep I tried this. I bent up a piece of scrap stainless steel to make a small heat shield for the sensor and a second piece which was fixed close to the rear of the exhaust manifold to further deflect the heat away. They were made to pick up on existing bolts.

I can't say if your jeep has the same problem but it's possible This TJ had a history of dropping onto 4 cylinders when hot. Turn it off for a while and it'd heal up. If you scanned it with the diagnostic computer it came up with the code for a coil pack failure, and the dealership changed this twice with no success.
Title:
Post by: prozac on April 07, 2007, 09:55:24 AM: Excellent description Mike!! I've just opened the bonnet and had a look :shock: :shock: :lol: :lol: :lol:

I'll have to get the manual out and look when I have more time.
Title:
Post by: Mike Pavelin on April 07, 2007, 11:03:40 AM: Don'r have pics i'm afraid, but the crank sensor isn't hard to locate, it's in a tight spot, though.
Title:
Post by: prozac on April 08, 2007, 01:55:47 PM: :oops: :oops: :shock: it's totally inaccessible from either side.

It's in for a big service in a week or so, I'll have a word with the service department and leave Mike's prognosis printed out in the car..... see if they can suggest anything.

Thanks for everybodies help.
Title:
Post by: Mike Pavelin on April 09, 2007, 08:49:09 AM: Access is a bit restricted on the XJ. If you're going to a dealership, Get them to scan the PCM for fault codes and see what comes up.
Title:
Post by: prozac on April 09, 2007, 09:08:03 AM: will do!!! Thanks once again Mike.
Title:
Post by: prozac on April 18, 2007, 09:11:55 AM: The story continues..... in for a 30k service (quoted £500) yesterday.
Collected car and was told it'd be £338 :wink:
I'll start googling but would appreciate any advice on what to avoid....
Title:
Post by: tim_aka_tim on April 18, 2007, 09:39:46 AM: Centre box? There's 2 'boxes' on an XJ, the cat and the muffler. Assuming it's the muffler, you can get an aftermarket rear section fitted at any exhaust place for cheap.

If you're looking online, look for 'cat-back' systems, which are from the cat er.... back!
Title:
Post by: prozac on April 18, 2007, 09:48:37 AM: Not sure then.....

Also they found 2 spark plugs were shagged so that may have been the power problem
Title:
Post by: tedthefed on April 18, 2007, 07:15:17 PM: Don't the boxs on the XJ's have a smallhole in them. On both of mine there is to let water out on first starting or something like that. (not a techie)
Title:
Post by: prozac on April 18, 2007, 10:37:40 PM: Yeah they have a little forward facing hole in the bottom of the first box..... I saw that too, will have another look tomorrow.