what did you do to your MJ today?

[Minuit]

49 minutes ago, 13 Legion said:

Well after working 14 hrs last night.....Called downstate to verify I had my ducks in a row. Got sent a temp insurance ID card as well as an in house form, from  State Farm, saying vehicle is insured as antique/ historic. Not enough. They need hard copies of course. After 15 minutes of going around in a circle I told them I’ll just register in another county. I told the lady ‘I have insurance and a current license, I’m good to go. You don’t want to plate it that’s your problem. I’m driving.’ It just irks me to know downstate Indy, the ones in charge, tell me I’m good to go, the people here tell me that’s just a call center they’ve never actually worked in a branch. Whatever.... to be continued....

Isn't bureaucracy just great?

 

Drove Mr. 89 about 10 miles to the dump and back yesterday. It did alright! Even after fully warming up, I still had a not-great but-better-than-before 20 psi of oil pressure at idle! Gotta do those control arm bushings though. I can feel it in the steering wheel, the caster is way under spec. The axle gets a little shaky under there too. Wouldn't mind having a cooling system that holds pressure either.

[13 Legion]

Still waiting for insurance paperwork.... decided to troubleshoot a turn signal gremlin... thanks Cruiser54 for the insight! Also found a burned out taillight bulb. Took off the taillight and bulb was pulled apart. I don’t drive often, mainly a garage ornament, but jeez how long has this bulb been in there???

[BustedKnuckleJK]

Found a swank new shift knob on Amazon for $15 that matches the thread pitch. It’s actually an OEM part for Honda Civic SI.

[GreasemonkeySC]

Found a swank new shift knob on Amazon for $15 that matches the thread pitch. It’s actually an OEM part for Honda Civic SI.

You can do an Amazon search for "M10 1.50 shift knob" and get pages of results!

 

I have the Hurst T-handle, OE fat head knob, aluminum ball, aluminum tall knob, and Dragon Ball Z #4.

 

[Ls2xjcomanche]

Installed tool box I got from Jeep Driver. 

[NHMJXJ]

Cheers Don ... It was a warm day today, so on it went!

 

 

[GreasemonkeySC]

Recently replaced a failed water pump, and put in a new thermostat. Flushed & filled the cooling system.
Everything went well until I towed a 1500 trailer down the interstate @ 80mph. 25 miles from home I notice the temp rise quickly, so I kill the AC. Temp doesn't drop, so I pull off to investigate.
Temp is holding at around 245° with the E-fan constantly running. I let it sit & cool for a bit, then check coolant. I find a muddy rusty nasty mess in the radiator.
I hooked the trailer to my wife's JKU, and back down there road I go. Temp holds at about 225°. We made it through family lake day, but just barely.

Now I gotta flush it again.
Anyone know a good coolant additive for rust prevention? One that's not snake oil!

The curious thing is that I have 2 TJ's, and a YJ. None of them have this issue, and I fill them with the same coolant & water.

[gogmorgo]

Most coolants are already full of rust inhibitors, so other than the various flush products if that's what you want, pretty well any additive is snake oil. Getting it up to operating temp can loosen up a ton of gunk that wouldn't necessarily come out just by running a garden hose through it. 

[GreasemonkeySC]

This is after a flush & fill with pre mix 50\50.

Chem tested - no head gasket leak!

Dash, thermostat housing, radiator cap.

It's running 225° with the AC on at highway, or city speeds. If I try to tow my #800 trailer it runs up around 250°, with or without AC.

It's never run this warm before. Just started yesterday.

 

I don't understand WTF is going on.

 

 

 

[GreasemonkeySC]

Starting to think my new thermostat isn't opening fully.

[FrankTheDog]

Most likely thermostat.

[jpdriver1]

repaired clutch line, discovered the new slave cylinder in trans leaks --- like a sieve 

 

attempted to locate the proper plug in for mystery connector under hood --- no luck

[GreasemonkeySC]

Starting to think my new thermostat isn't opening fully.

And I checked today. Thermostat opens properly.

[RustyRodder]

Started my open cooling setup- truck wasnt going over 160 unless sitting, then it goes up to 175 and stabilizes/declines.  Expected a stuck open thermostat, but nope (maybe its a 160). 

[89 MJ]

Got a rust free tailgate

[Minuit]

Bypassed my heater core, to test whether or not the heater control valve had an effect on A/C performance. Turns out, that yes it does, and yes, there were reasons for Jeep to include it that become apparent once you want some really cold air in your MJ. I always knew there was some change, but I had no numbers to back it up. Here's the first draft of one of the pieces I'm working on for the coming-soon A/C writeup.

 

The Heater Control Valve

For as long as there have been Jeep forums, one of the most common pieces of wisdom you'll see thrown around is "get rid of the heater control valve and throw it in the trash". It's a 30 year old piece of plastic with coolant flowing through it, so it presents a definite possibility for leaks. I threw mine away several years ago on this advice. However, Jeep wouldn't have installed it for the first 12 years of the XJ's run if they didn't have a reason for it. That reason is very much connected with the subject of this writeup, so let's take a look at it.

 

Why worry about any of this? Let's look at a diagram of the MJ's HVAC system.

(source: 1990 Jeep factory service manual)

 

 The A/C evaporator is the first thing the air passes through after leaving the blower motor. This is to provide dried air (via the A/C evaporator) no matter the blend door position - very useful when defrosting the windows, and if the driver would prefer to have dry heat in the cab. Unfortunately, that means that everything that happens to the air after it leaves the evaporator is out of the A/C's hands. Even if you want the coldest possible air, the cold air still has to pass through the rest of the HVAC box and out to the vents, in relatively close proximity to the heater core. If coolant is flowing through the heater core, the heater core will be very hot, and it will warm up everything around it. As it flows through the hot ducting, the air will warm up a little.

 

The heater control valve was Jeep's solution to this problem. When the driver commands the coldest air possible, the valve closes and prevents hot coolant from flowing into the heater core, which prevents the heater core from warming up the surrounding duct work. Since even cold air has to pass right next to the heater core, this can and does make a difference to A/C performance. Even if you don't have A/C, not having any hot coolant flowing through the interior will help keep cabin temperatures down.

 

In Renix-era models, the valve is closed in the "OFF" and "VENT" positions. In all other positions, the valve is closed any time the temperature selector is in the "full cold" position. In HO models, the valve is closed only when the temperature selector is in the "full cold" position. At all other times, the valve is open and coolant flows freely through the heater core.

 

So, let's put some numbers to this. To simulate a working heater control valve, I bypassed my heater core and went for a ride.

 

To summarize my results, all else being equal the air at the vents with the core bypassed is between 3 and 7 degrees cooler when the truck is at operating temperature. These measurements were taken on two back to back days at a temperature of around 83 degrees. In the world of A/C performance, seven degrees is a big difference. It can separate a "decent" system from a "good" system. In my case, this allowed for air in the high 30s at speed on an 83 degree day. I live in the humid South, and I want all of the A/C performance I can possibly have, so a seven degree improvement is worth the effort.

 

After this test, I've changed my stance on keeping the valve. If you are interested in maximizing your A/C performance, I suggest that you keep the heater control valve, and replace it if it is leaking. The valve is still available in the aftermarket and you may be able to find Mopar valves in inventory. The 1991 and later part number for 2.5L and 4.0L engines is 56005900. The 87-90 part number is 52003226 for 4.0L engines, 56002522 for 2.5L engines, and J3222290 for the 2.1L diesel engine. For an open cooling system, use the later part.

[Ωhm]

You did it the right way, as designed. Only other way is manual ON/OFF valve (Winter/Summer). Also don't forget A/C MAX setting for even more cold.

[Minuit]

17 minutes ago, Ωhm said:

You did it the right way, as designed. Only other way is manual ON/OFF valve (Winter/Summer). Also don't forget A/C MAX setting for even more cold.

Ah yes, I forgot to mention. For the heater core bypass test, I did all of my measurements on NORM (so that it's cooling the 80-ish degree outside air rather than the ??? degree air inside the truck) on the second fan speed. On both days, it was between 80 and 85 degrees outside. Max makes the air slightly colder (and cools faster because it's recirculating) but makes nowhere near as much difference as bypassing the heater core made. I wanted to keep things simple and consistent for this test.

 

Max A/C at the highest fan speed makes the truck into a meat locker and keeps the compressor running almost all the time. I love it!

[tiltonb]

I took it in and had new tires put on it.  I even replaced the spare tire, it had the original tire on it, and dry rot had the best of it.  I put the spare under the bed but that little cable seemed a bit sketchy so I ratchet strapped it for added safety. 

[RustyRodder]

I have my open cooling 85% done, but I can't drive the Jeep indefinitely due to the bigass crack in the frame by the steering box  How did that happenw ith stock tires??

[coolwind57]

On 6/4/2019 at 10:25 PM, tiltonb said:

I took it in and had new tires put on it.  I even replaced the spare tire, it had the original tire on it, and dry rot had the best of it.  I put the spare under the bed but that little cable seemed a bit sketchy so I ratchet strapped it for added safety. 

 

Good plan.  I never did this to my spare.  Three weeks ago, I was going down the highway and almost had an accident.  I heard a huge sound and my truck's rear end went slightly skyward.  I thought I ran over something that I didn't see in the road.  I pulled over and my spare tire was missing with only a dangling, frayed cable hanging down.  My license plate wiring was in shreds with some minor rear bed sheeting distorted a bit.  

 

So now I need a new spare tire holder, a new spare tire, and a half hour fixing my license plate wiring.  More importantly, I could had killed somebody with my airborne spare at 75mph.  

 

I'll be strapping my new spare down with extra security, you can bet on it.  

 

Strap down your spares, fellas.  Don't rely on the stock cable alone.  Don't be a coolwind57.  

 

 

[floridaftwman]

Went to move my MJ today and found that my parking cable broke and the emergency brake is stuck. Didn’t have the time to release it....


Sent from my iPhone using Tapatalk

[Pete M]

On 6/4/2019 at 7:54 PM, Minuit said:

Bypassed my heater core, to test whether or not the heater control valve had an effect on A/C performance. Turns out, that yes it does, and yes, there were reasons for Jeep to include it that become apparent once you want some really cold air in your MJ. I always knew there was some change, but I had no numbers to back it up. Here's the first draft of one of the pieces I'm working on for the coming-soon A/C writeup.

 

The Heater Control Valve

For as long as there have been Jeep forums, one of the most common pieces of wisdom you'll see thrown around is "get rid of the heater control valve and throw it in the trash". It's a 30 year old piece of plastic with coolant flowing through it, so it presents a definite possibility for leaks. I threw mine away several years ago on this advice. However, Jeep wouldn't have installed it for the first 12 years of the XJ's run if they didn't have a reason for it. That reason is very much connected with the subject of this writeup, so let's take a look at it.

 

Why worry about any of this? Let's look at a diagram of the MJ's HVAC system.

(source: 1990 Jeep factory service manual)

 

 The A/C evaporator is the first thing the air passes through after leaving the blower motor. This is to provide dried air (via the A/C evaporator) no matter the blend door position - very useful when defrosting the windows, and if the driver would prefer to have dry heat in the cab. Unfortunately, that means that everything that happens to the air after it leaves the evaporator is out of the A/C's hands. Even if you want the coldest possible air, the cold air still has to pass through the rest of the HVAC box and out to the vents, in relatively close proximity to the heater core. If coolant is flowing through the heater core, the heater core will be very hot, and it will warm up everything around it. As it flows through the hot ducting, the air will warm up a little.

 

The heater control valve was Jeep's solution to this problem. When the driver commands the coldest air possible, the valve closes and prevents hot coolant from flowing into the heater core, which prevents the heater core from warming up the surrounding duct work. Since even cold air has to pass right next to the heater core, this can and does make a difference to A/C performance. Even if you don't have A/C, not having any hot coolant flowing through the interior will help keep cabin temperatures down.

 

The valve is closed in the "OFF" and "VENT" positions. In all other positions, the valve is closed any time the temperature selector is in the "full cold" position.

 

So, let's put some numbers to this. To simulate a working heater control valve, I bypassed my heater core and went for a ride.

 

To summarize my results, all else being equal the air at the vents with the core bypassed is between 3 and 7 degrees cooler when the truck is at operating temperature. These measurements were taken on two back to back days at a temperature of around 83 degrees. In the world of A/C performance, seven degrees is a big difference. It can separate a "decent" system from a "good" system. In my case, this allowed for air in the high 30s at speed on an 83 degree day. I live in the humid South, and I want all of the A/C performance I can possibly have, so a seven degree improvement is worth the effort.

 

After this test, I've changed my stance on keeping the valve. If you are interested in maximizing your A/C performance, I suggest that you keep the heater control valve, and replace it if it is leaking. The valve is still available in the aftermarket and you may be able to find Mopar valves in inventory. The 1991 and later part number for 2.5L and 4.0L engines is 56005900. The 87-90 part number is 52003226 for 4.0L engines, 56002522 for 2.5L engines, and J3222290 for the 2.1L diesel engine. For an open cooling system, use the later part.

 

you should do a DIY writeup on all that.  

[Minuit]

17 minutes ago, Pete M said:

 

you should do a DIY writeup on all that.  

That will be an appendix to the final A/C write-up. There's a thread about it somewhere in the pub.

[Pete M]

13 hours ago, Minuit said:

That will be an appendix to the final A/C write-up. There's a thread about it somewhere in the pub.

 

and bring those tools with you when you eventually come help me with the wiring