Troubleshooting the Hurricane

Dead mouse in the exhaust?


The Emergency Engine Troubleshooting Chart (50K GIF) from the 1957 CJ-3B Owner's Manual is still not a bad place to start when you're trying to figure out why your engine misses, fails to start, loses power or overheats. Or you can do what Mike did, and go straight to the CJ-3B Bulletin Board, which is almost as good as getting all the Willys heads to come over to your garage to help work out the answer.

Bill Ness and friendsMike: "I think I got ripped off on the 3B. Don't get me wrong, I like the Jeep very much, it was completely re-done in '94. The guy I got it from said it also has a new crate motor. (Had 13,000 when I got it in 2000, now 14,400.) The Jeep has no rust and looks very good. The detail of original factory condition remained with no major modification from the guy I got it from. He said the tires are even the original, but I don't know.

"When I got the Jeep it ran very good. After a tune up, oil change, etc. it ran the same. As a matter of fact the one day I had to take it on the highway it went 65 mph! The Jeep never smoked or backfired. Then one day it was hard to start, top speed was 40-45. Going up any hill, we're talking small 1% to 2% grade, was 2nd gear 25mph. Most of the time I had to drive in 2nd with no power to shift to third. I put a new carb on, Pertronix electronic ignition and another tune up. It runs good but no power at all. I have checked all the things that need to be checked. The best example I can think of, is when people put sawdust in the gears to quiet them down, it works for time than major trouble. That's how my engine seems -- it was great for a while, then trouble one thing after another. I never did check the valves for correct adjustment -- maybe that could be it, but it does not have any ticking or unusual valve noise or smoke."

Jerry Brown: "It sounds to me like the exhaust valves may be improperly adjusted. You may be able to adjust them and restore performance. If they have gone too long they may have to be ground or replaced. Check the compression and valve clearance. This is done via the access plate on the side of the engine (not the pan on top)."

Wes Knettle: "Since it ran perfectly when you bought it ('Then one day it was hard to start, top speed was 40-45.... Most of the time I had to drive in 2nd, no power to shift to third.') then the reduction in power was sudden. Short of a broken cam or valve chain part, I would not suspect the valve adjustment. Especially since you have gone electronic ignition and new carb and it runs fine but no power. I would have started the day the performance suddenly went bad with a compression check, induction inspection for leaks or partial blockage and exhaust inspection for blockage, a thorough inspection of the vacuum plumbing and PCV system, then check fuel pump output. Any of the above will allow the engine to run well at low power but restrict ability to reach full power output."

Anon: "And the mouse went up the pipe..."

Wes: "Aha! Someone else who has been stymied by the dead mouse in the muffler. I have found restricted exhaust causing Mike's symptoms many times. Most folks tend to overlook the exhaust as part of the engine breathing system. They tend to concentrate on air and fuel in and end up spending a lot of money on carbs and valve adjusting just to end up replacing a plugged muffler or bent (pinched close) pipe. Simply put: It must be able to SUCK & BLOW to GO."

PuzzledMike replied: "The fuel pump is less than 6 months old, the exhaust is about 7 months old. The exhaust has 5x as much pressure coming out the tailpipe then my 5.0 Mustang. When I first got the Jeep I thought something was wrong because if you stood behind the tail pipe it would almost blow you over. (Not that bad but I think you get the picture.) Same with the new exhaust, no bad bends or pinched, just tons of exhaust pressure."

Wes: "We are all still assuming that you've got good compression checks, the timing has been confirmed to be correct, the centrifugal advance is giving the correct # of degrees advance at the correct RPM and the induction system is unrestricted from the air filter to all 4 intake valves."

Mike: "The compression gauge reads 95 on cylinders 1 and 4. But zero on 2 and 3. I guess since it never misses, idles fine, does not use oil, I blew the compression idea off. I would guess this would tell me I've got a blown head gasket between 2-3, or incorrect valve setting?"

Ed Wilson: "I think I would get the head off and see what's going on. With the head off, you can inspect valves, seats, gasket, etc. There is just no way to be sure (peace of mind!) without this inspection. I replaced an exhaust valve on mine in an afternoon with no special tools except the torque wrench for the head bolts. A Service Manual will help here, especially for the head bolt torque sequence."

Mike: "I took the head off and am taking it to NAPA to have it hot tanked. The gaskets will be here by Wednesday."

Ed: "Bad gasket, huh? If it's not already on your list, might want to get the head checked for warpage while you're in there. ALL heads can get out of square due to improper torquing or a bad overheat. In fact, when we did my F4 rebuild I had the machinist deck the head .020. This trues up the mating surface and in my case brought the compression ratio back up a bit after the cleanup bore in the cylinders. I'm starting to sound like Mom, but wondering why the gasket was bad."

Mike: "Had the head checked out, the machinist said it was in very good shape. Not warped, had him grind the valves -- only wanted $35.00 to do it. I think what happened is the head was not bolted down (torque) the same all the way around. Some of the bolts came out very easy. Don't know if this is true but he said that the head gasket that was on there requires re-torquing."

Thanks to Tech Editor Andy Stock and all the contributors. Aso Dave Hatch for the photo of Bill Ness and friends looking at Bill's 3B in Wisconsin, and the unknown photographer of the photo from Australia. -- Derek Redmond

See more engine advice on the CJ-3B Tech Tips page.

FacebookVisit CJ3B.info on Facebook.

CJ3B Home | Contents | Search | Links | 3A and 3B Community

Last updated 3 November 2004 by Derek Redmond redmond@queensu.ca
All content not credited and previously copyright, is copyright Derek Redmond