I've got an 88 F250 with a 460 that is only used for towing. Truck has 50K miles on it.

Two weeks ago while coming back from the coast, towing my boat, during the tow most intense uphill climbs I got clearly audible lifter noise (at least that's what it sounded like). As I let out of the gas the noise faded away in about 15 to 20 seconds.

Any ideas on this? the noise was very similar to the lifters ticking that I hear for just a bit after startup, but was louder. It only happened after I'd had my foot all the way into the throttle, transmission had downshifted, and was really into the grade.

Never has happened before- not sure if I need to take the truck into the shop, or what. Could this be something as simple as the wrong viscosity oil not working well with the hydraulic lifters under extreme loads?

Truck wasn't running hot, although the fan clutch did kick in during the climb.

Any thoughts would be appreciated.

 

Sounds like spark knock to me.

 

Cracked exhaust manifold ?

 

I'd go with preignition, spark knock, like critter said. Check your timing and vacuum advance, maybe put some better fuel in it and see what it does..

 

thanks for the suggestions. I do that tow fairly regularly through the offshore season (that trip was the first of the year) and may even try to get a buddy to record the sound on the next trip through the coast range.

It doesn't sound like the typical spark knock, but that doesn't mean that's not what it is. I'd also thought about it being an exhaust leak. Does sound more like it's on the right side.

Will be two weeks before I get another shot at the salt.

 

Exhaust manifold leak is common. Check the back bolt on the passenger side (mine is broken off, most likely happened on its own).

Also, do you have an oil pressure gauge in your truck?

 

The truck does have an oil pressure gauge although it's just a range gauge not PSI or numerical values. Oil pressure has always been constant with the truck, on the low side of the normal range, if I work the truck hard enough the needle will center up on the gauge.

I sure hope the ocean lays down enough to tow to the coast in a week and a half. I'll have the passenger video the gauges and the sound, if the truck does it again, on the two hard pulls coming back.

Have done a lot of coast range tows with that truck, the noise is a new one.

thanks again for the replies

 

Since you are working your 460 to the max I would put premium fuel in it for these trips. Also a higher viscosity oil would not hurt either in case it is a lifter noise. I have had lifter noises like you "just a bit after start-up" but never in my 460 engines after that. So make sure your oiling system is working properly. As for exhaust leaks, on my two 460s and now a 557 I have had in my truck over the years you could hear an exhaust leak almost all the time if there was one. They usually do not come an go. But that said still checked your exhaust system out.
Also good for you for checking this out. I know when I was pulling 12,000 lbs. of a grading tractor and trailer for 25 years. Any strange sound or movement of the truck and trailer got my attention fast.
Good luck and let us know what you find out.