Knocking in a HP500EFI
 

I have a question for all you motor heads out there. I ran the boat for the first time last week end. Started fine, no noise, plenty of oil pressure, everything fine. I ran for about 2-3 hours and had to out run a thunderstorm to a marina. When I got in out of the rain, I checked things out and found oil in the bilge. Checked and I was a little low, looked like it came out the dip stick(?). Added some oil and started the motor and I had a low energy knock coming from the top and back of the motor. I idled it home and put it on the trailer. Got this feedback from the mechanic today.

Originally thought it was a fuel injector, nope.

Now, after talking to Mercury High Peformance, he thinks it is a roller follower on the cam, may need new cam shafts and roller rockers and exhaust valve springs. He says oil in the bilge was from a front seal leak on the drive (not there last fall when winterized).

He said that this cam/rocker problem is not unusual for the 1998-1999 HP500's with approximately 150 hours on them. Mine is a 1999 with 175 hours on it.

Anyone else have this problem?:confused:

Sorry to hear about your motor problem!
I think I'm having the same problem. My very faint knock/noise is @ idle only after I have run it for awhile and idle. Is your knock intermittent? My kinda comes and goes. My 1999 HP500 Carb. and has about 73 HRS on it. My motor runs great, although, this weekend when I started it, I got a little puff of blue smoke when I first started it. Let us know what your mechanic finds out. I'm getting more concerned about this now after hearing your problem.
Thanks,
Dean

Mine starts intermittment but after it warms up is constant. Changes with the rpm, sure sounded like a lifter to me when I first heard it. The mechanic said that there are no metal shavings anywhere (yet).

Let's see if anyone has had this problem and I will be sure to post what it ends up being.

Boatinbill,

Sorry to hear about your problem. I had the same problem on my 502mag. oil coming out of the dipstick tube is not a good thing.
looks like you might have some blow by going on.
I would suggest you do a compression and leak down test.

JDELO

Jeff sounds right, they did have some small problems with the roller lifters, and also the inner valve spring would break with less than 170 hours, I think it was the carb version most of the time, also check the flappers on through hull exhaust, they will break
and the sound will travel it sounds like the motor but it can be the flappers good luck

canada jeff i to had same knocking noise it was in the quick&quite ck butterflys in exhaust, no big deal to fix

You may have been getting small amounts of water in the oil and when you ran it hard to beat the storm the oil got hot and flash boiled the water out of the oil. This will push the dip stick out and also push the oil out. WAS THE DIP STICK PUSHED OUT ? When the oil level got low the lifter didn't get the oil it needed and also may have colapsed. Don't take a chance -repair it.

This is a common problem with some of the HP 500 carb's. I have the same motor and at about 150 hours, lost a valve spring. Luckily it did not hurt ther cam or valves. Leak down and compression tests on the other cylinders checked out fine, but upon closer inspection we found 3 inner springs broke. Hopefully you will not need a cam or lifters.

Thanks for all the input, it is not in the exhaust flappers (the knocking is there whether in SIlent Choise or not), appears to be in the valve train. Mechanic working on it as we speak. The good thing is that I caught it so early that it is hard to locate and it appears no other damage has occured.

I have forwarded all the input and experiences shared here, thanks much.

I will post what it ends up being as well as what had to be done to correct.

Mama tryed, I need a ride this weekend!!!!!

Thanks for all the input, it is not the exhaust flappers, knocking was there both in Silent Choice mode as well as straight through.

The mechanic is working on it as we speak, appears to be in the valve train. The good thing is I caught it so early that it is hard to locate. Appears no other damage.

I will post what is found as well as what is done to repair it.

Mama tryed, I need a ride this weekend!!!!!!!!!!!