Engine problem on my M38A1

alfa59 · Post by **alfa59** » Mon Dec 05, 2011 2:37 pm

Hi,
Greetings from overseas Belgium (Europe). I recently purhcased this vehicle which comes from the Dutch army(Nekaf).
The problem I get is that at a certain rev , there is a noise such as "clack, clack, clack)? This disappears when I rev higher or lower.
This happens when I am driving or standing still.
This noise does not happen at idling
We have changed the coil, put new sparkplugs but problem continues
Anyone an idea what that could be ?

I also find that at idle the steering wheel is vibrating - is that normal?

thanks
Chris

Post by **wesk** » Mon Dec 05, 2011 3:23 pm

If the engine does not idle smoothly that roughness will be transmitted to the frame and body and steering wheels can then vibrate.

The clack noise is best diagnosed with a listening device (stethoscope) to narrow down the physical location of the noise. IE, this type noise can be made by the fuel pump arm (listen at the fuel pump) or the valve lifter (listen at the side valve cover and the top valve cover), or the crank end play, listen at the front lower edge of the block casting.

oilleaker1 · Post by **oilleaker1** » Mon Dec 05, 2011 6:06 pm

A lifter with too much clearance, too much end float on cam, bad rod bearing or main bearing. To check for a bad rod bearing disconnect one plug wire at a time and rev up the engine. If the knock goes away, that cylinder has a bad rod bearing. Listen with a tool as Wes mentioned to locate better also. Some guys remove the fan belt briefly to eliminate water pump and generator. Good luck, hope it's simple. John

alfa59 · Post by **alfa59** » Tue Dec 06, 2011 9:48 am

Hi,

thanks a lot for the feedback. We will do the check as such.
One more thing:

When the M38A1 is standing still, the vibration in the steering wheel increases with the higher rev's. Any idea what that could be caused of ?
Engine mounts have been replaced.

thanks Chris

oilleaker1 · Post by **oilleaker1** » Tue Dec 06, 2011 1:51 pm

Engine vibration is noticeable in all my Jeeps to a minor degree. Sometimes it shows up in the dash with loose metal parts. Check your steering column for looseness. Shaft bearing, bolts , dash bracket etc. Does your engine have a noticeable miss or shake? Bad spark plug/wire? broken or loose mounts? Bad transmission mounts? Body hitting the bellhousing? Could even be your noise. My M38A1 had a upper bell housing bolt worn through the large removable floor covering! John

Post by **wesk** » Tue Dec 06, 2011 2:03 pm

Engine contact with the body, frame or steering system can cause your issue. Exhaust system contact with the steering or clutch linkage can cause it also. Please note that the first hanger for the exhaust is bolted solid to the frame behind the tranny cross member. Installing a rubber isolator found on many civilian installations will help.

alfa59 · Post by **alfa59** » Tue Dec 06, 2011 2:39 pm

Sounds like I will have an interesting winter work !! Was thinking to buy you a ticket to come to my country !!
thanks for the info and I will keep you posted when we found it.
Chris

oilleaker1 · Post by **oilleaker1** » Tue Dec 06, 2011 5:49 pm

Belgium Barley Pop!!!!!, Heck yes, I'll be glad to assist!

John

Cacti_Ken · Post by **Cacti_Ken** » Wed Dec 07, 2011 4:47 pm

My M38 steering wheel vibrates at low rpm also It will line out with just a small increase in rpm.