The "Joycemobile" .. aka Buffys new XJ

[Slayercommathe]

 

The old one was called the Joycemobile by a lot of my friends - its kinda right cos in the show it was her car not Buffys. 

Anyway, we digress. Point is, I got a new project. The old one was cool, but it had fairly ugly dents in the rear panels. Think it had been shunted at some point and the tow bar subframe had transferred the shock. Whenever I put it on show, I covered up the dents with strategic placing of banners, but it needed sorting. 

I'd been quoted £600 to fix the bodywork, but instead this one turned up at a good price:

 

Its newer (2001), and its the anniversary model. So all nice things. I will be swapping a few parts over from the old one so as to keep this as a screen replica.

However, first there are some things to fix:

• a few electrical gremlins (central locking, indicators) but I'm an electronics person anyway so not concerned.
• airbags need replacing (not sure if this is just a case of fitting replacements or if the sensors need to be changed too?)
• something went wrong with the cooling system - it overheated and blew a hose off, or maybe the hose happened first. Friend thinks its a stuck thermostat, but we haven't looked yet. The steam came from the drivers side of the engine block, thats all I know atm.
• I want to have grey cloth seats again, but this has black leather. I cant swap with my old one because these are electric/heated. Not sure if electric cloth seats exist? If so I want a pair.
• Need to have a good look underneath and hope there's no nasty surprises.

 

So here we go again. Show car build #2. Lets hope its not as nail bitey as the first one.

 

Edited November 13, 2022 by Slayercommathe

[V]

4 hours ago, Slayercommathe said:

airbags need replacing (not sure if this is just a case of fitting replacements or if the sensors need to be changed too?)

 

I guess they haven't detonated already otherwise you will want a new dash panel and steering wheel pad. What's the reason for needing new airbags?

[Slayercommathe]

10 minutes ago, V said:

 

I guess they haven't detonated already otherwise you will want a new dash panel and steering wheel pad. What's the reason for needing new airbags?

 

They have, and I can get new pads

[V]

Can you get brand new recently manufactured airbags or 21 year old stock? The original airbags were made by Takata but not part of the global recall. I have a 60th Anniversary XJ and I would prefer my airbags were removed as unexpected detonation becomes more likely every year. As far as I know, I am legally stuck with them.

[Slayercommathe]

18 minutes ago, V said:

Can you get brand new recently manufactured airbags or 21 year old stock? The original airbags were made by Takata but not part of the global recall. I have a 60th Anniversary XJ and I would prefer my airbags were removed as unexpected detonation becomes more likely every year. As far as I know, I am legally stuck with them.

 

Ah, no not actually new. When I said I could get new ones, what I meant is replacements. Didn't know they were prone to misfiring. I had my other xj for a few years with no issue

[V]

12 hours ago, Slayercommathe said:

Didn't know they were prone to misfiring.

The XJ airbags are not known to be prone to misfiring.

 

However, nobody knows how many years an airbag will last. Airbags in an old Jeep with potentially unstable explosives inside them is going to be a thing as time goes by. The youngest XJ air bag is 21 years old, the oldest is 27 years.

 

The Takata airbags that went off like a grenade in the driver's face were often found to have suffered from corrosion. I would prefer the law be changed so that airbags (explosive devices) are compulsory removed from all vehicles every 20 years. If they cannot be replaced with brand new (less than 3-year old) airbag then the vehicle is recorded as being airbagless after that point so the airbag lamp is not tested at MOT and insurance does not treat it as a modification.

Edited November 14, 2022 by V

[digger]

How is the airbag 'tested' at MOT?

I can't see it was the thermostat they are designed to fail safe ie open. Sounds more like the hose to me which failed under normal pressure, or maybe the head gasket.

Edited November 14, 2022 by digger

[V]

2 hours ago, digger said:

How is the airbag 'tested' at MOT?

The airbag isn't tested, only the airbag system check warning lamp. It has to come on when the ignition key is turned or the ignition ready state is activated and extinguish within something like 7 seconds.

 

2 hours ago, digger said:

Sounds more like the hose to me which failed under normal pressure, or maybe the head gasket.

Hopefully, a hose fault is the cause. But overheating is bad news for a '0331' head. Check all of the usual culprits for overheating and coolant loss first.

 

The worst case is It could be a cracked head. All of the 4.0L 60th's had the dreaded '0331' casting that was introduced in 1999. If the head gasket looks like the prime candidate, get the head crack tested before replacing the head gasket. If the head is not cracked and you are going to use that head again, you must get the head skimmed at a machine shop. It is a complete waste of time and money if you don't. Insist that the machine shop crack tests the head before skimming so they don't waste money skimming a scrap head. Personally, I wouldn't put a '0331' back on an engine unless it was a 'TUPY' head.

 

If it is a cracked head you will most likely find the crack between cylinders 3 and 4 on the spark plug side. It's a waste of time replacing the head with another of the same vintage. You can't use an earlier model head without ignition and exhaust mods but you can use an improved 'TUPY 0331' from a late 2002 to 2006 4.0L (Grand Cherokee, Wrangler) . The TUPY heads can be identified by shining a torch down the oil filler cap and looking at the head casting. If you see the word 'TUPY', buy it - You will need it some day.

 

Alternatively, there are some brand new Chinese heads on the market. Some have the mark 'HTK' where '0331' should be. I have no idea if these are any good or not, but they look like TUPY clones.

 

Edelbrock make an aluminium head (50169) which is very well made performance product. It's not cheap and is likely to set you back £3K or more at the current exchange rate if you can find one in stock to import.

Edited November 14, 2022 by V
Removed left overs from a version of sentence that didn't make sense

[digger]

Actually, unless there's any reason why not that  V knows that I don't, if you are skimming the head you might as well take enough off to increase the CR ratio. It s not difficult working out how much to remove . Ask if you need !  I've often thought the compression was low( 8.2 :1 I think)  raising it to say 9:1 would improve your acceleration a bit and more importantly the bottom end off road. You might even get away with a bit higher, after all we have to use super fuel anyway!

[V]

31 minutes ago, digger said:

Actually, unless there's any reason why not that  V knows that I don't, if you are skimming the head you might as well take enough off to increase the CR ratio

The engine was designed to run on lower octane fuel that was more common in the USA than in the UK. A typical British regular petrol grade is 95 RON which is 4 points skewed on the equivalent US measurement (PON). 95 RON UK is roughly the same as 91 PON USA. From memory, I think the lowest fuel octane useable in a Jeep 4.0L that I have tried is 88 PON, some rural filling stations sell 87 but I haven't tried my Jeep on it.

 

If you are only using E5 Premium, that will likely be 98 RON so Digger's suggestion of raising the compression ratio makes sense. There is quite a bit of headroom before knock occurs. I don't know if it would make a noticeable difference in emissions, performance or fuel economy but trying to find a TUPY head without having to buy the entire engine is proving a challenge. I think I would leave a few skims left on a TUPY head for the future just in case.

[digger]

Good point of 'V's re leaving a bit of skim.

I wonder how far you can go with a jeep head, assuming no issues with rockers etc. 

I'm not certain and probably a bit out of date but I think you can go up to 10:1/10 1/2 :1  or more.

In any event you can always add octane booster. I have some really wild stuff on my shelf . the tin wasn't cheap (a few years ago) but you don't need much.  What I do know is that higher compression  will noticeably improve power at low/ mid range  rpm , The possible penalty is a loss of  actual  rpm at the top end. i don't know how strong the engine is at higher rpm. I've never looked in the head of a 4.0L Jeep head so I don't know a lot about it. If there any 'thin' metal projections etc I would clean all those up, which will also reduce the risk of pre detonation. You would probably need a slightly different  plug. You can get a plug chart/book  from NGK or someone. They are full of useful info re plugs. I would start just one grade cooler of the same pattern or you could ask NGK.

I wonder what CR/ spark plugs  Edenbrock use with their fancy head?  My guess is that the CR and gas flowing will make up the majority of their power gains. I doubt that they fit bigger valves because that would ruin the very bottom end. A lot of stock motors gain a lot by just getting the valves sealing  and working properly.

Ps I misunderstood what you meant by MOT test re airbags 'V'!

 

Edited November 14, 2022 by digger

[UKTJ]

I have also seen that a company called Clearwater in the US make a replacement head, which I believe is similar to the Tupy one.  No direct experience, just passing on something I read elsewhere.

[V]

11 minutes ago, UKTJ said:

Clearwater in the US make a replacement head, which I believe is similar to the Tupy one.

I think it could be the Chinese made head. I have not examined either in person, but the advertising photos I have seen of each online look suspiciously similar.

 

The post-2006 after market '0331' head made by 'Alabama Cylinder Head Inc' had a good reputation at the time. They are no longer trading so I don't know if their product became the Clearwater product or if both were always a Chinese made head.

 

Hesco made a small quantity of aluminium 4.0L heads for a while but this would be a very rare find.

 

Hopefully, Slayer's problem is just a hose or pump failure and the engine was stopped in time before it overheated. Water in the oil or oil in the coolant could indicate head gasket failure, warped head (stretched bolts), a cracked head or a problem with a radiator integrated oil cooler. I've seen a top hose blow off after a water pump failure and before the radiator safety cap blew. I think the rubber formulation of hoses has changed over the years. Hoses made in the early 1990's don't appear to last as long as hoses made since 2000.

 

[UKTJ]

Yes @V, it may well be the same head being sold by a number of people, a lot of that seems to go on these days.  If I understand it the issue with the '0331' head is a complete lottery, some on the US TJ forum I frequent have done 300,000 miles on a 2000-2002 '0331' head  others have been a lot less fortunate on much lower mileage.

Edited November 14, 2022 by UKTJ

[digger]

Re Edenbrock head. I've just found one of these on offer on EBay uk stock ,free shipping for £2597.95.

The combustion chamber volume is 55cc. Does anyone know the stock volume?

 

https://www.ebay.co.uk/itm/354383825136?mkevt=1&mkcid=1&mkrid=710-53481-19255-0&

campid=5337674827&toolid=10049&customid=742716354-14-185175361.1668500954

Edited November 15, 2022 by digger

[UKTJ]

12 hours ago, V said:

 

The post-2006 after market '0331' head made by 'Alabama Cylinder Head Inc' had a good reputation at the time. They are no longer trading so I don't know if their product became the Clearwater product or if both were always a Chinese made head.

 

Appreciate this thread is being taken off topic, but thought it worth sharing this for completeness.  I have just done some research and it looks like Alabama Cylinder Head Inc. became part of ProMaxx Performance, from the ProMaxx website:

”ABOUT PROMAXX PERFORMANCE

We are a family owned business that began in 2012 by purchasing the remnants of Patriot Performance and Alabama Cylinder Head Exchange. We specialize in all types of cylinder heads, from diesel to performance. Our performance line has become a passion. Our mission is to provide the best performing cylinder heads on the market, at a price that cannot be beat. With over 30 years of racing experience, at nearly every level bracket; pro Mod and Prostock. We have learned what works and what does not on the street and the strip. We have designed a complete new line of performance heads that meet or exceed the big names in the industry. We also have customer service that is second to none, giving attention to each customer’s questions and concerns. We are a relatively small company that realizes that each customer is important.”

 

These heads are sold by Quadratec for ease of purchase for a UK based buyer.

[V]

Here is one of the Chinese cylinder heads, shipped from China.

 

For a Jeep Chevrolet 4.7L V8 - It looks like a Jeep Cherokee 4.0L i6 head to me.

In aluminium - I guess the shipping weight will be a clue. The combustion chamber looks like the head is iron.

Comes with 10 valves - I guess you would have to supply the missing two yourself.

 

My guess is that the foundry in China that was making the cylinder heads for the license built Chinese Jeep Cherokee kept on making them and is now the only source for brand new replacements worldwide. They probably get resold from wholesaler to retailer worldwide under different brand names.

[Slayercommathe]

10 hours ago, UKTJ said:

Appreciate this thread is being taken off topic, but thought it worth sharing this for completeness.  

 

Hey no problems with the off topicness. Its been good to learn about this stuff.

No news this end, tbh I haven't been out in the cold and dark lol

[digger]

On 14/11/2022 at 21:13, UKTJ said:

Yes @V, it may well be the same head being sold by a number of people, a lot of that seems to go on these days.  If I understand it the issue with the '0331' head is a complete lottery, some on the US TJ forum I frequent have done 300,000 miles on a 2000-2002 '0331' head  others have been a lot less fortunate on much lower mileage.

Yes the different times of satisfactory use are interesting. I'm convinced that whilst different 'whatever' in manufacture may be an issue, equally important is how much over heating occurs, correct anti freeze etc and of course correct bolt tightening up procedure.

[V]

On 13/11/2022 at 18:41, Slayercommathe said:

I want to have grey cloth seats again, but this has black leather. I cant swap with my old one because these are electric/heated. Not sure if electric cloth seats exist? If so I want a pair.

I really like the cloth seats in my '93 but the interior including the door cards are all looking a bit grubby after years of off road use. I have been thinking about an interior refresh using custom fit neoprene seat covers which would be more practical for me. The US company that makes them also makes custom fit cloth covers and they are now available on rockauto.com . A seat cover would work with your heated leather seats and is likely to be cheaper than professionally retrimmed seats in the UK. They may also offer custom fabric choices, no harm in asking.

 

If you do decide to use seat covers made for a Cherokee be careful when ordering. The European models had removable rear seat head restraints, the US models didn't have rear seat head restraints. Some of the front seat US models were high back, whereas all of the European models were low back with removable head restraints.

 

 

[digger]

I don't know for sure with an XJ  but there may be another issue if you decided to go down the route of retrimming  the seats. 

My YJ has really good seats but the foam padding inside the drivers seat is starting to squash down at the entry side. I tried hard to sort this out when I first had the car and my local upholsterer is very good and reasonable prices. A major improvement was achieved but the thing is the 'foam 'padding in side is a one piece pre moulded profile. This  is no longer available and I haven't found an after market  product either. 5 years later the piece  inserted is starting to squash again!  For this reason I am thinking that I will have it 'repaired ' once more (side bolster repadded) and put both front seats into storage whilst using different  seats. I am hoping to have secured a pair of TJ seats but if I'm not able to get them I have found a few car makes whose seats will look good and be comfortable for me.

You might consider stripping out the heated seat pads etc from leather seats and fitting them into cloth seats. Just a thought because years ago I had to replace a failed unit in a Ford and it was easy!

Edited November 16, 2022 by digger