cycling engine noise

[2deuce]

The R6602 gas engine in my 5- ton has noise that sounds like the valve train isn't getting oil for 3-4 seconds then quiets for about the same time then gets noisy again. I'm going to pull the rear valve cover because the best I can tell, that is where it originates. Has anyone experienced this behavior ? and can possibly tell me what to look for.
Thanks,
Greg

 

[Towman2277]

Hey, I've got a gasser R6602 also. I have had this noise on cold startups, but it goes away with 5-8 seconds and doesn't continue. I will ask a good friend who is a Guardsman who works on these trucks and get his professional opinion. I'll holler back later on today. Steve

 

[2deuce]

Mine is doing it during and after warmup. I haven't run it very much at all and none lately since I'm working on the clutch. It seems like the valve train runs dry-gets oil-and repeats. Oil pressure is good on the gauge. I'm puzzled Thanks Steve for looking into this. Greg

 

[Towman2277]

Hey, I got with my buddy and he said one of two things could be the problem..... Pull the rear valve cover, and make sure the drain-back holes are nice and open, without any old oil sludge build-up, to prevent drain back of oil, and 2) most likely he said it could be the wrong viscosity oil (He said use multi weight to help) such as 10w40. If neither helps, holler back and lets see what can be done.

 

[2deuce]

I haven't looked at the drainback holes yet but I did change the oil to delo 400 15-40W. I did that before I got it running cause I could smell gas in the oil. Replaced the fuel pump too. I did pull the front valve cover because when I was adding oil back in, oil started running out from under the cover if I poured too fast. Found that the gasket was installed incorrectly along time ago, it had slipped inside. I haven't determined for sure that the noise comes from the back valve cover, it just sounded like that standing next to the truck. When I get the clutch taken care of I'll start the engine and figure out where for sure it comes from. Thanks for your help. Greg

 

[m139h2otruck]

Update on noise?

Any update on the noise? I bet that the broken clutch/bearing parts were the source. Our R6602 is not really very noisy in the valve train at idle or slightly above. At 1500 to 2500 the rest of the noise cancels out the valves and all you can hear is the bellowing of the big exhaust. On the road, the gearing makes just as much noise as the engine. Crawling around the jobsite in 2nd low range, the truck is really not that bad. The 30 ton rock truck and the dozers make a lot more noise.

 

[Towman2277]

RE: Update on noise?

Any update on the noise? I bet that the broken clutch/bearing parts were the source. Our R6602 is not really very noisy in the valve train at idle or slightly above. At 1500 to 2500 the rest of the noise cancels out the valves and all you can hear is the bellowing of the big exhaust. On the road, the gearing makes just as much noise as the engine. Crawling around the jobsite in 2nd low range, the truck is really not that bad. The 30 ton rock truck and the dozers make a lot more noise.

Hey, does your's also have the 14:00/20's on it, and what is your top speed?? Mine will run 57 mph on a flat surface, checked with a GPS, hauling about 2 tons on the bed. Just curious.

 

[2deuce]

RE: Update on noise?

I haven't been able to get the time needed to fix the clutch yet. I don't think the clutch is the source of the noise but I hope it was. The noises sure did seen to come from the valve train. When I first posted this question I had no idea what was wrong with the clutch. Once I got it apart I was surprised that I didn't hear anything from the clutch with all the damage there. I didn't feel anything in the clutch pedal either. I hope to get the clutch back together next weekend. Greg

 

[m139h2otruck]

M139 Road Speed

Yes, our truck still has the original 1400x20 NDCC tires, Denman on the front and Silvertown BFG on the back which are dated 1961! Rear hubs were flipped and the spacers installed on the outside with the rear tire/wheels reinstalled as singles. Load rating on the tires is less than a tank of water alone so we don't dare carry anything while traveling between sites. Top speed as best we can judge is 45-50 on the interstate with level going. Have to check timing as I think it may be slightly retarded. Carb is a brand new Zenith and based on fuel use, lean conditions are not the problem. Truck seems slower than it should be, but it runs great and there are no problems or funny noises other than the gearing noise at speed which all of these trucks tend to have. I am sure that if we removed the interconnecting drive shaft between the tandems, that the truck would handle better, but in the conditions we use it, this would not be the best move.

 

[Towman2277]

RE: M139 Road Speed

Yep, there is no way on getting great gas mileage with a bridge truck but it sounds like it runs great though. Do you happen to have any pics on the way your truck looks with the rear setup as you have it?? I thought of running mine the same way....and one thing i've found on most gasser bridge trucks that i've played with, is the knob that you pull to "choke" down the motor before you turn off the ignition...trace it down to the carb....and the butterfly that turns when you pull the knob...it is usually already only open "slightly" instead of "wide open". Mine felt sluggish, and would barely hit 50, but once i adjusted the butterfly, it will run now until it redlines!! Right at 57 mph!

 

[m139h2otruck]

Carbs

The Zenith carb now on our truck does not have the "degasser" valve like the Holley had. Truck will run-on some when hot, but not bad. Also have to check governor setting as the engine barely will rev to 2500 with no load, and manual says that we should see 3100± with no load. Hate to mess with a good running engine though. Anyone ever check compression pressures on these engines? Manual says that we should see 120 psi if we did. When we got the truck, the fuel pump was failing, and it got run for about 15 min. with the oil pan full of gas. Have been afraid that the diluted oil may have affected the rings, but the oil pressure checks out at 50-55 psi hot with a mech. gage.

 

[Towman2277]

RE: Carbs

Its probably your governor setting, as sitting with no load it should "free spin" to around 3000 easily. Even if you had bad rings (highly unlikely) it would still spin up higher than 2500 with no load.