1998 Cherokee 4.0 Ltd - Project

[Fourpot]

20 hours ago, spookie the aardvark said:

Simple and elegant, like that a lot - good find Does it fit any Jeep or just your one?

here's the website... https://www.azzysdesignworks.com/   Looks like only XJs, but with a variety of gearbox and transfer case combinations.

[Fourpot]

Fitted the radiator and fan assembly. Test fit only, but it's fine. A few more things to do with it out, to get better access to the front of the engine bay, then I can get it bolted back in properly and put some coolant in it.

[spookie the aardvark]

3 hours ago, Fourpot said:

Fitted the radiator and fan assembly. Test fit only, but it's fine. A few more things to do with it out, to get better access to the front of the engine bay, then I can get it bolted back in properly and put some coolant in it.

That is one awesome bit of kit - love it to death

[spookie the aardvark]

3 hours ago, Fourpot said:

here's the website... https://www.azzysdesignworks.com/   Looks like only XJs, but with a variety of gearbox and transfer case combinations.

I googled it after I asked the question and your right only for XJs ........................ he has a lot of nice stuff on there but nothing for the WG/WJs

Cant quite understand what he ment by not being able to break into the WJ market - surly there must be loads of them in the States just as there are over here. But hay ho maybe be it isnt cost effective. Could be he was, at some time, run over by a WJ

[Marcus Durand]

This is such amazing stuff, I look on in awe! 

[Fourpot]

Fitted the upgraded transmission oil cooler today. Spent ages trying it in different places, factors determining its location: some cooling air-flow, protection from being battered, not in the way of anything else. The original cooler was apparently only ever an option on these Jeeps, so it'd probably run happily without it, certainly in the UK, but just in case I do any mad off-road stuff on a hot day, it'll help stop the gearbox getting too hot.

Although it doesn't look very well protected at the moment, it'll sit behind the front bumper and have a layer of mesh in front of it too.

I've ordered some new hose as the original hoses aren't now long enough.

That front bit with 'Jeep' on hasn't seen the light of day since February!

 

[spookie the aardvark]

Coming together nicely Fourpot - only downside is all the nice new shiney stuff has disapeared

[Fourpot]

Set about tackling some of the wiring that had been consigned to the bin during the strip-down, namely the injector part of the loom. I've inserted an extra connection for no other reason than to be able to isolate it if future diagnosis is required or if it burns up again like the original did. Still have to do the wires that go to the throttle-body, intake manifold, and coolant temp sensor.

[frosty]

On 15/11/2020 at 19:44, Fourpot said:

Fitted the radiator and fan assembly. Test fit only, but it's fine. A few more things to do with it out, to get better access to the front of the engine bay, then I can get it bolted back in properly and put some coolant in it.

very nice set up of your electric fans, on my TJ, the viscus fan has been removed, and a bigger electric fan fitted, i have removed the original sensor, and fitted the one in the picture below, it is a aluminum unit, very well made for racing cars, when you order it ,you can specify the temperature you want it to switch at, you could also have more than 1 switch, so the fans come on progressively for your multiple fan set up. 

[frosty]

i have also a switch on the dash, to "override OFF" the electric fan for deep water / mud situations. 

[V]

2 hours ago, frosty said:

i have also a switch on the dash, to "override OFF" the electric fan for deep water / mud situations. 

I have always wondered if a soil moisture sensor had fast enough reaction time to do this automatically with the necessary additional electricals.

[frosty]

2 hours ago, V said:

I have always wondered if a soil moisture sensor had fast enough reaction time to do this automatically with the necessary additional electricals.

hi Vince, it is a possibility, but given the environment where my jeeps operate, i think it is better to keep things simple. 

[Fourpot]

I don't now if anyone spotted the deliberate mistake from a few bits back. I'd replaced all the cooked wires with a new section for the injectors. All nicely soldered in just after I posted (Nov 18th) I noticed my plonkery! Ages back I had fitted four-hole injectors iin stead of the original one-hole things. This meant that the original loom plugs no longer fitted the new injectors, so I bought some adapters. As these made the fittings stand up high, I also had to add an extension adapter to No. 3 injector as there wasn't enough room under the throttle cable bracket. Now I've rewired the lot, I should have taken the opportunity to bin the adaptors and get new plugs to suit the later injector type.  So now I have...  some cable conduit thrown in makes it all much tidier!

[spookie the aardvark]

OMG Fourpot ............................... "plonkery" ? ........................................... the automotive god has fallen before our eyes

[V]

Fourpot, I just noticed the heat wrap on your manifold. A few months ago I wouldn't have thought twice about doing the same. Now I am not so sure. In the summer I had version 5 of my exhaust system fabricated, this month I am on version 7. Version 6 was heat wrapped.

 

The belly pan area on my XJ is cramped and the coil spring rear has always caused problems with the exhaust up to now. With version 5 I had a Cherry Bomb M80 sat alongside my transfer case downstream of the catalytic converter. It sounded great, but had a lot of heat build up around the transfer case due to the large diameter muffler being close to everything under there. My downstream O2 sensor plug and socket melted. Version 6 had a Supertrapp fitted to the M80 to reduce the noise and I used heat wrap all over the section of the exhaust covered by my skid plates to reduce heat. I wrapped the M80 and pipework right up to the catalytic converter outlet where I had an expensive sleeve clamp to enable easy exhaust removal for maintenance.

 

I'm not sure when I noticed, but I had probably done around 500 miles before my replacement O2 plug and socket arrived. I took the belly pan off to rewire it and noticed aluminium that had melted and dripped on to the skid plate where it cooled and solidified. The sleeve clamp had an aluminium wedge inside it and it had completely melted out. The sleeve was loose on the pipes. The heat wrap had retained so much heat in the cat-back part of the system that heat was building upstream of it.

 

Aluminium melts at 660 degC, so the temperature downstream of my cat clearly achieved that. Regular petrol engine exhaust gas temperature (EGT) upstream of the cat is typically between 350-600 DegC with 900 DegC being a maximum for most catalytic converter survival. I was worried that I had melted the core of my new cat but after removing the downstream system I could easily see that it was still intact.

 

I am now wondering if a heat wrapped manifold will create high EGT going into the catalytic converter, or higher heat soak going back into the head. For version 7 I removed the M80 and all of the heat wrap. I now have a chambered muffler by my rear bumper with a plain stainless pipe run from the cat. The air space in my belly pan no longer gets as hot as it did. There is plenty of air flow now to keep the entire system cool from the downpipe to the muffler.

 

I haven't measured my current EGT, but I had a bung installed for a thermocouple downstream of the cat just in case. It's running so much cooler now that I don't need to measure it.

Edited November 24, 2020 by V

[Fourpot]

Interesting stuff V!  I don't have a belly pan so I'm guessing there's not a huge build up of heat in the lower part of the engine bay. My objective with the wrap was to reduce heat around the inlet manifold, which seems to be considerable. I don't have any aluminium bits on my exhaust anywhere and the wrap only goes as far as the cat, not round it or past it. All the O2 sensor wires I have re-routed so they get away from the exhaust as early as possible. I have some heat shield stuff on a shelf somewhere as I was going to put it above the exhaust in those areas near the cat etc. where it runs close to the body. I haven't yet as it hardly gets more than warm. All the underneath of my XJ is covered in a thick layer of Waxoyl stuff and it hasn't melted (or, heaven forbid, caught fire) but as you say, the areas post cat/wrap may now be hotter than before. Time will tell...

[Fourpot]

11 hours ago, spookie the aardvark said:

OMG Fourpot ............................... "plonkery" ? ........................................... the automotive god has fallen before our eyes

Ha ha... I don't even know if it'll start and run yet! 

[V]

3 hours ago, Fourpot said:

but as you say, the areas post cat/wrap may now be hotter than before. Time will tell...

 

My problem was heat travelling upstream towards the catalytic converter. I wasn't expecting conduction upstream to be something I should be concerned about.

 

Since my last post, I have been reading posts on other forums about wrapping manifolds and there are definitely people for and against it. However, there does seem to be more 'against wrapping' opinions from long term owners that have already done it themselves. Some are saying that only internally and externally ceramic coated headers can survive wrapping.

 

I found this comment in response to a warranty void clause for an after market header:

Quote

OK, I'll stick my hand up.
I destroyed a high quality set of headers on a Ford pickup in less than two years by wrapping them. When unwrapped, the metal next to the flanges was paper thin. The headers blew out at the flanges, where the temperature is the highest. Steel oxidizes at room temperature, the rate increases as the temperature rises. Hotter it gets, the faster the steel goes away...Chem 101 stuff.
If the manufactures say not to wrap, would you suppose they have a reason?

 

I found this video with temperature measurements between stock, after-market and wrapped manifolds that does not surprise me now.

 

Last year I replaced a stainless manifold that had done 12 years of service. I bought another exactly the same to replace it but the old one was in such good condition that it was repairable with welding. I have a benchmark now for life expectancy both stock and after market XJ manifolds. My stock manifold did 6yrs exclusive road use + 6 yrs on/off road, my stainless manifold did 12 years on/off road. I have seen a lot of stuff online today that suggests that non ceramic coated wrapped manifolds last between 1 and 3 years. I had no idea about the reduction in service life until I started investigating.

 

You have put a lot of time, effort and money into your Jeep and it's entirely your decision how you build it. I have made up my mind today on the issue. Please take some time to look into it further and decide for yourself.

 

Don't watch this if you are happy with the exhaust wrap.

[AlexK]

My understanding of heat shielding and wrapping has been that it's best done on 'cold' components rather than 'hot', i.e. don't wrap the hot components as you're just trapping the heat in.  Instead, wrap or shield nearby components that should be kept cool to protect them from the heat source.  So, don't wrap exhausts, but do apply shielding to floor pans, wrap nearby wiring, etc.

[Fourpot]

1 hour ago, PDB said:

My understanding of heat wrapping and heat shielding is they are not the same in concept. This comes from my days of modding a Prodrive impreza. The heat shielding is to protect components as Alex states. But wrapping the exhaust is to increase flow with higher temps. But your exhaust has to survive the higher temps! The wrap is designed to keep the heat in to the exhaust, so in effect also acts as a heat shield to other components.

 

I have been looking at wrapping my exhaust where exposed from back behind the belly guards, but this is only to reduce the risk of causing grass fires when overlanding in dry climes. Some kind of open kevlar weave should do it. This would allow heat to escape, whilst providing a cooler surface for grasses to stroke as I pass/stop.

You're right, and I have come to the use of wrap as a sort of multi-role answer. This stuff is used in racing to keep the exhaust gases hot and so make them flow better (somehow) (and in racing, a new manifold every so often is not a big deal). I have tried to see if I can make some sort of shield betwixt exhaust and intake manifold but I gave up, so for the benefit of the intake air temperature, I'm pursuing a cold air intake (within the next few episodes of this thread). Finally, just general keeping it cooler under the bonnet. A lot of the wiring in the engine bay has been replaced as it was getting brittle and wires were melting into each other (I'd wondered if there may have been a serious overheat or fire under a previous ownership, but there's no other evidence of that).

I heed everything that V has said and spent ages umming and aahing about it before deciding to go for it. I'll certainly be checking the metal regularly, even with the stainless steel thick stuff it's made of. I've also been thinking about exhaust wrap for my Triumph Bonneville, although there's no real 'for' argument in that situation other than it might look cool. 

[Fourpot]

1 hour ago, PDB said:

My understanding of heat wrapping and heat shielding is they are not the same in concept. This comes from my days of modding a Prodrive impreza. The heat shielding is to protect components as Alex states. But wrapping the exhaust is to increase flow with higher temps. But your exhaust has to survive the higher temps! The wrap is designed to keep the heat in to the exhaust, so in effect also acts as a heat shield to other components.

 

I have been looking at wrapping my exhaust where exposed from back behind the belly guards, but this is only to reduce the risk of causing grass fires when overlanding in dry climes. Some kind of open kevlar weave should do it. This would allow heat to escape, whilst providing a cooler surface for grasses to stroke as I pass/stop.

Get a bigger lift kit? 

[V]

I wish I had really thought about that earlier, it sounds like a sensible approach. I guess having experienced a few vehicle fires over the years I have become more focused on what gets hot.

[V]

I went over to my storage today and took a close-up photo of the stainless manifold that I used for 12 years. The photo shows the worst bit (blueish colour) and the condition of the rest of the tubes. The manifold has never been wrapped but has been washed free of mud quite a few times.

 

[V]

50 minutes ago, Fourpot said:

A lot of the wiring in the engine bay has been replaced as it was getting brittle and wires were melting into each other (I'd wondered if there may have been a serious overheat or fire under a previous ownership, but there's no other evidence of that).

 

I think it's just a combination of a hot engine bay and time. I will need to tap you for info on the injector plugs as I will have to rewire my fuel injectors and the LPG injector emulator harness at some point soon.

[spookie the aardvark]

12 hours ago, Fourpot said:

Ha ha... I don't even know if it'll start and run yet! 

We true believers have faith in the automotive deity raisng Lazarus from the dead ............................. godly "plonkery" not withstanding