New Member, New Comanche

[tbrand]

Hey y'all,

 

I've been lurking for a few weeks, as I picked up a 1989 Comanche recently. It has 122,500 miles, 2wd 4.0/5-Speed (I think it's the Frenchie, but I'm not sure). It ran all right when I bought it, and better now with a new fuel filter/plugs/wires. I'm totally new to the Jeep scene, and relatively new to wrenching beyond oil changes, so bear with me.

 

1) It has an oil leak. I'm not sure where, but most of the underside is pretty well coated and grimy, and I've gone down about a quart in two weeks/400 miles of driving. Are there any particularly notorious trouble spots I should check out?

 

2) Gas gauge is stuck. I don't know if it matters as far as diagnosis, but I have the full gauges (tachometer/oil pressure/etc)

 

3) What should oil pressure be? It reads above 40 at startup, but can get down near 20 during driving.

 

4) I get a hiccup in acceleration around 1800-2200 RPM. It just seems to bog down, and then gets going again if I keep my foot down.

 

5) Above 2600 RPM, it starts sounding a bit like a diesel. I have no idea if this is normal - family cars have been mostly Hondas.

 

6) Any other advice/tips?

 

Thanks for any wisdom you can throw at me. I've been meaning to pull up the carpets and see how the floors are - that's on the list for this weekend. I live in Arizona, so I'm optimistic.

[MJRemi]

Welcome to the Club!! :cheers: I'll leave the answers to your questions to the guys who know alot more than I. If you've been following the site you know you'll get plenty of help. Good luck with the truck and try to add some pics and your location on your next post. :thumbsup:

[TrailReadyMJ]

Hey y'all,

 

I've been lurking for a few weeks, as I picked up a 1989 Comanche recently. It has 122,500 miles, 2wd 4.0/5-Speed (I think it's the Frenchie, but I'm not sure). It ran all right when I bought it, and better now with a new fuel filter/plugs/wires. I'm totally new to the Jeep scene, and relatively new to wrenching beyond oil changes, so bear with me.

 

1) It has an oil leak. I'm not sure where, but most of the underside is pretty well coated and grimy, and I've gone down about a quart in two weeks/400 miles of driving. Are there any particularly notorious trouble spots I should check out?

Rear main seals are notorious for going out. This does not require removing the transmission, just the oil pan, but still not the easiest task. You should be able to find a good write-up by searching around

 

2) Gas gauge is stuck. I don't know if it matters as far as diagnosis, but I have the full gauges (tachometer/oil pressure/etc)

Since your other gauges are working, this could be anything from a stuck/saturated float, to a bad wiring connection to the gauge itself.

I'd start at the sending unit at the tank. If you have a multi-meter, you can check the resistance between the sending unit and ground. If I remember right, this is the purple wire at the tank. Then drive around for a while and test again. If the resistance doesn't change, it's the float/sending unit in the tank.

If it does change, check for bad connections, or it could be the gauge itself.

 

3) What should oil pressure be? It reads above 40 at startup, but can get down near 20 during driving.

That's a normal reading. The FSM calls for a range of 13PSI @ 600RPM to 37-75PSI @ 1600RPM and higher. Also these gauges aren't the most accurate, and to get a true reading, a mechanical test gauge should be used.

 

4) I get a hiccup in acceleration around 1800-2200 RPM. It just seems to bog down, and then gets going again if I keep my foot down.

You mentioned plugs and wires, what about the cap and rotor? Also see next answer...

 

5) Above 2600 RPM, it starts sounding a bit like a diesel. I have no idea if this is normal - family cars have been mostly Hondas.

Shouldn't sound like a diesel, but won't sound like a honda either :D This could possibly be the knock sensor on the side of the block. The plug on mine used to get loose every so often, and it would sound a bit like a diesel under load.

 

#4 and #5 could easily be related to each other

 

6) Any other advice/tips?

Welcome! Congrats on the MJ!

 

Thanks for any wisdom you can throw at me. I've been meaning to pull up the carpets and see how the floors are - that's on the list for this weekend. I live in Arizona, so I'm optimistic.

[SW86]

if its not the rear main seal leaking oil then its the rear of the valve cover or oil pan gasket. which if you change the oil pan gasket might as well do the rear main seal while your in there.

[Geonovast]

Two other somewhat common places for a bad oil leak are the oil filter adapter O-rings, and there's a possibility your passenger UCA smacked the oil pan. Check the lip of the pan around the hump for the oil pump.

[tbrand]

Thanks for the tips. I finished with the distributor cap and rotor today, and between that and the new plugs/wires, my seat-of-the-pants dyno has really noticed an increase in power. I can't believe how much the mechanic charged us to do that bit of tuning up when we took my wife's Honda in earlier this year - really not a difficult job. The hiccup in the acceleration seems to be gone, but the diesel-type sound still remains. It's hard to hear over the rattle of the muffler trying to fall apart, but it's there. Haven't gotten to checking the knock sensor yet - apparently working on the Jeep doesn't count toward getting the house ready for company tonight.

 

The oil appears to be coming down from the area specified by arrow 1, and drips off the bottom by arrow 2. More likelihood of RMS troubles?

 

Do other, more general photos belong in this thread, or over on the Projects board?

[tbrand]

So, after dropping out the bearing cover, I'm stuck trying to get the upper half of the seal out. One write-up recommended a hammer and small Torx screwdriver, but I don't want to mar any surfaces in there. Someone told me to try a brass punch, but Sears, Lowe's, my local Ace Hardware and Harbor Freight are all non-carriers. Where does one find a brass punch (or something else suitable for this task)?

[HOrnbrod]

A hard plastic chop stick worked for me. :D You can find brass drift punches in any good local hardware store, but they will scar too if used too energetically.

[Geonovast]

I was able to get mine out fairly easily by having someone turn the motor over by hand while I tapped on it. Just make sure you're both going the same way, and spin the motor over a few times with you not under the truck to make sure you won't get squirted on.

[Oizarod115]

I was able to get mine out fairly easily by having someone turn the motor over by hand while I tapped on it. Just make sure you're both going the same way, and spin the motor over a few times with you not under the truck to make sure you won't get squirted on.

also, you can loosen the remainder of the main-caps, (not much, just break them loose) and spin it over while tapping on the seal. Thats what got mine out. (she was STUCK)

[cluricaunne]

Welcome to the club, can't wait to see some pics

[tbrand]

A hard plastic chop stick worked for me. :D You can find brass drift punches in any good local hardware store, but they will scar too if used too energetically.

 

I found a screwdriver from some old tool kit, that had a fat Philips on one end and a flat piece just the size of the hole on the other. I imagine that it used to go in some interchangeable screwdriver handle. Anyway, that did the trick on the upper seal, and with the help of my lovely wife, I got the oil pan back in. Whew!

 

Now, we wait and see if I have any drips.

 

Thanks for all the advice, everyone! I really appreciate it. :D

[90MJext]

while taking a diesel class, the instructor showed us a trick by finding a screw that matches the hole in the crank and grinding the head down until it matches the bearing.

[tbrand]

Welcome to the club, can't wait to see some pics

 

 

 

 

I've put the lower dash back on, and my next project is probably to get the seat fabric sewn back up - it's torn on the top. That is, unless the household CFO approves a CD player.

[TrailReadyMJ]

Looks like a clean truck, nice find!

[Automan2164]

while taking a diesel class, the instructor showed us a trick by finding a screw that matches the hole in the crank and grinding the head down until it matches the bearing.

 

Yep, thats a good trick for doing main bearings in the block, but that won't work for the rear main. ;)

 

Rob L.

[mythreesons]

........

I've put the lower dash back on, and my next project is probably to get the seat fabric sewn back up - it's torn on the top. That is, unless the household CFO approves a CD player.

 

For my last Jeep purchase, I watched the shelves at Walmart for clearance radios. Picked up one that has a USB port in the front and a remote which is handy when driving.

 

I don't have an iPod, but I do have flash drives. So I load my CD music onto them and they go into the Jeep. That way I don't have to fool with dropping the front plate to put in a CD and they take up less space. You can get a lot of music onto a 2GB flash drive. It works great for me with the stock wiring and stock speakers. I only needed something that sounded better than my singing voice (which is not good).

 

Also, welcome and nice truck! :wavey:

[tbrand]

Looks like a clean truck, nice find!

 

Thanks man. I still need to get the carpets up and check the cab for rust, but the rest of the truck is pretty darn solid as far as I can see - thank God for Arizona!