Knock under load..

[Skyr]

Ok my 98 Offroad 3.0 liter 5 spd has a knock/rattle under load.. Sounds dead on like mains are going out but is holding great oil pressure.. Ive wracked my brain and all my friends brains trying to figure it out.. So far Ive changed plugs, wires, fuelfilter and upgraded to even 91 octane gas trying to get it to stop...None of which has changed it abit. Clutch is strong so no broken spring in it..Also have cleaned the injectors in it (via many a bottle of different types of cleaner). Any thoughts or ideas here would be greatly appreciated.. Also I have no engine codes/lights on.. Gonna try seafoam on the topend today(my last idea)..150k miles on it also...So im open to any sudjestions here..

 

[1badexplorer]

Mine started the same knock at 150K too. I did the same things you tried and nothing helped. I ran out of ideas and decided that I will figure it out when whatever it is breaks competely That was 45K miles ago. Its still running just as strong as when I bought it with 100K on it. So I would assume that its not the bottom end. Because I doubt you can put that many miles on a motor with a bottom end noise. My noise is still there today. If I down shift or I am gentle on the throttle peddle it goes away. I'm thinking its something cracked or loose in the valvetrain, only time will tell. If you figure it out PM so I can try it on mine.

 

[Viper Command]

When I destroyed my motor mounts, it made the same sounds

 

[Skyr]

The Seafoam thru the brake booster vacum line helped the power out alot..But still same issue...motormoants are fine..Knocking is probably the wrong way to discribe it...its more of a low hollow rattleing... Sounds just like the main bearings are shot.. But oil pressure is still good..