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Discussion Starter · #1 ·
I have a 76'cj5 with a 258 and only 69,000 miles on it. I run Mobil Syn. oil and a mechanical gage.

If I drive for 20 miles on the highway then slow down to go through town a tapping noise can be heard. The noise comes and goes in no piticular patteren. If I drive in the city for a while it sometimes goes away all together. The oil pressure runs from 15 - 20 idle to 40-50 highway at 55 mph.

The noise does not seem to bother engine performance, but it is just bothering me and I need to take care of it. I thought it maybe the fuel pump and it was leaking so I replaced it, but did not help the noise.

Any thoughts would be welcomed, and Thanks in advanced.

Lunatic
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If the tapping will accelerate when you do it sounds like it may be a hydralic lifter with some gunk in it. Pour a quart of ATF in the crankcase, run for about 10 minutes, rev the engine now and then. Then change your oil. The ATF usually will help clean out the lifter if thats the problem.
Pigpen

 
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Discussion Starter · #3 ·
Your oil pressure sounds good...and the previous post is correct about the lifter and what to do about it....however, lifters ususally maker their noise at startup and then go away. My money would be on an exhaust leak at the manifold. The bolts are notorious for comming loose...and an exhaust leak at one end can sound just like a lifter tapping. It is not uncommon for the noise to go away as the engine heats up (all the metal parts are expanding)...hence, your's get quiet because of the city driving...i.e., engine runs hotter.

Let us know what you find....

John......southern CA
84CJ7, 3"lift, 32"BFG, 4.10's, ARB Locker, Solid Axle's, Durabak
 
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Discussion Starter · #4 ·
Thanks for the info on the exhaust leak. I checked and that was not it. It is definetly comming from inside the engine. I never heard of the AFT idea. Is there any drawbacks to using it. I read the earlier post on it not working for the valves.

I only have 1500 miles on this oil change and that was alot for syn. Can I wait or should I just bite the bullet and do it this weekend. The sound is driving me crazy.

Lunatic
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Discussion Starter · #5 ·
Those guys both gave excellent advice, one more thing I've noticed with my 258 and running the Mobil 1 - the engine is a little noiser when that oil gets up to temp and starts getting thinned out. I know that some of the noise seems to be from the valvetrain having less of an oil cushion to slap around on compared to when I ran dino oil because it just gets thicker(well more viscous really) the hotter it gets. The synth stuff stays pretty thin but protects those moving parts better. Good luck.

Sully '84 CJ-7 Laredo 258 w/HEI

 

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/wwwthreads_images/icons/smile.gif From one lunatic to another......do you have a by-pass to the fuel tank from the fuel filter?....in other words, is your tank set up with (1) Suction line to fuel pump; (2) Return line to tank; (3) Tank vent. And.....do all those lines run up to the front? The suction to the fuel pump, the return FROM the fuel filter to the tank....and the VENT from the tank to the charcoal cannister./wwwthreads_images/icons/crazy.gif

CJDave
Quadra-Trac modified by the crack moonguy/wwwthreads_images/icons/wink.gif/wwwthreads_images/icons/smile.gif/wwwthreads_images/icons/tongue.gif transfer case team.
 
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Discussion Starter · #7 ·
I was just looking at that today. I do have a return line to the tank and from the Charcoal canister to the tank at least that is what is labled. The only one that is not hooked up on the canister is the one labled To Carb. The condition of these lines are mostly unknown, I just have not crawled under the jeep to look.

Could one of these lines cause the problem???

Thanks

Lunatic
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/wwwthreads_images/icons/smile.gif Sometimes if you DO NOT have the fuel return line going back to the tank where the fuel pump can pump gas in a circle, two things can happen: (1) it will make the engine have a tendency to vapor lock in not-even-very-hot weather, and (2) it makes the fuel pump sound funny since there is so little fuel being pumped at idle or slow cruise. Remember....the engine only "cocks" the spring in the fuel pump, the spring itself pumps the fuel. We are using the metal three-port filter which has an inlet port centered in the end wall of the filter, an outlet port centered in the opposite end wall of the filter, and a by-pass port in the outlet end wall but very offset. By rolling the filter so the by-pass is higher than the port which feeds the carb, EVERY BUBBLE goes back to the tank and doesn't try to vapor lock the carb/wwwthreads_images/icons/smile.gifPLUS...our fuel pump has some fuel moving through it all the time and it doesn't sit there beating away and sounding wierd./wwwthreads_images/icons/crazy.gif OH YEAH!!! My moonguy-in-chief/wwwthreads_images/icons/wink.gifof all fuel systems just ran in and reminded me to tell you that the "Carb" hose on the charcoal cannister goes to the bowl vent on the carb......and he wants you to slap a fuel filter in that line to make sure your carb doesn't accidentally get a snootful of charcoal should the cannister go kaflooey and begin puking the black stuff out. A clear fuel filter would be nice/wwwthreads_images/icons/smile.gif

CJDave
Quadra-Trac modified by the crack moonguy/wwwthreads_images/icons/wink.gif/wwwthreads_images/icons/smile.gif/wwwthreads_images/icons/tongue.gif transfer case team.
 
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Discussion Starter · #9 ·
Thanks, I do have a 3 port fuel filter and the return is on the top (I think) will check tomarrow. As for the to carb from the canister I have no idea on which port on the carb. The carb has about 4 or 5 open spots (capped) for a vacum hose. The carb is not the original, I looked today and I think it said eldidge.

thank you again to everybody

Lunatic
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/wwwthreads_images/icons/smile.gif the carb port that goes to the cannister.......oops!....there are a couple of hoses that go to the carb....one is marked "bowl vent" one is the "purge" port....that goes to the side outlet on the PCV valve, and there is the "signal" port and that goes to the side outlet that hooks to the vacuum advance. None of this really has anything to do with the noise you hear, but I wanted these little moonguys/wwwthreads_images/icons/wink.gif/wwwthreads_images/icons/smile.gif/wwwthreads_images/icons/crazy.gifto feel good about looking all this stuff up./wwwthreads_images/icons/wink.gif

CJDave
Quadra-Trac modified by the crack moonguy/wwwthreads_images/icons/wink.gif/wwwthreads_images/icons/smile.gif/wwwthreads_images/icons/tongue.gif transfer case team.
 

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yes i think sully has hit the head of the nail on this one.. those 258's are useally loud anyways.. and syn. will bring that out more than reg. oil..

survival is instinct, but living takes guts
 
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Discussion Starter · #12 ·
I guess that I will look at the vaccum and gas lines. I then will try to do the ATF in oil to try to help clean out the engine. This thing wasn't driven much before I bought it. And I know nobody did maintenance to it, so the oil wasn't changed on a regular basis.

I'll let everybody know what happens.

Lunatic
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/wwwthreads_images/icons/smile.gif For several years in the late 80's and early 90's I kept myself in dirt cheap transportation by buying GM Diesel cars which the owner's had given up on. Like they would get some bad diesel and grow algae in the fuel tank, plugging up the tiny sock that was in there. Anyway....some of these cars had a lot of spider webs and leaves holding them down to the driveways and the engines would be dormant....big time....!! I always used Berryman B-22 and it was a real miracle worker when if came to freeing up the valves and lifters. It was always the same....they had put a brand new fuel injection pump on and the problem was algae in the tank. It would take me an afternoon sometimes to get them going because they had usually fried the starter cranking on it too. And when it did finally fire with WD-40 as a persuader, it would smoke and rattle pretty bad. Sometimes it would smooth out before I even had the whole can of Berryman poured into the crankcase.
I know that there are a lot of "Oaklahoma Fixes" for sluged up engines, but it was just easier to buy a can of Berryman's and have done with it. When I was just beginning to "do cars" an old friend of ours who came out to Californy during the Dust Bowl was my chief advisor on revitalizing old cars which had often been driven six blocks maximum for fifteen years and were using oil like crazy. His treatments always worked, but I just cannot recall exactly what they were. We also used Bardahl quite a bit for stuck piston rings./wwwthreads_images/icons/crazy.gif

CJDave
Quadra-Trac modified by the crack moonguy/wwwthreads_images/icons/wink.gif/wwwthreads_images/icons/smile.gif/wwwthreads_images/icons/tongue.gif transfer case team.
 
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Discussion Starter · #14 ·
I will try to find the ones your talking about or something similar. The darn thing runs really good, its just this intermitent noise that bothers me.

It took me along time to get this Jeep I just don't want to treat it like the POS cars that I had.

Lunatic
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