Quick Sanity Check Here - Pinging

[TwoBallScrewBall]

Hi.<br /><br />I've got a new 3.0 in my boat. Runs great, except for some strange behavior at WOT. If I run wide open for about a minute, I start to get a little pinging. If I back the throttle off the tiniest bit it stops. WOT with me alone is 4500, if I back down to like 4400 (really) it stops. <br /><br />First time it did this it sounded pretty bad. I didn't run wide open for the rest of the day. <br /><br />It has been getting progressively better. I checked the timing. Initially it was about 6* when it should have been 4*, so I reset it. <br /><br />The only difference beside that is that I have been slowly adding more new gas to the tank. I bought the boat in September, don't know how long it sat for. I filled the tank for the maiden voyage then, it took about 8 gallons in it's 27 gallon tank. Then the engine blew that same day.<br /><br />That gas sat all winter till last month. I got the new engine running and filled the tank again after breaking in the cam and messing around with the engine running on the muffs, took 3 gallons.<br /><br />Ran about 1/2 of that tank out breaking in the rings and the rest of the engine. Did not run WOT except for small bursts of acceleration so no pinging then. <br /><br />The next tank of gas had the worst pinging at WOT, and was the first time I let the engine spin up to max RPM. <br /><br />I have filled it about 3 times since then, each time about 5-10 gallons. I am using 89 octane since that's what the engine calls for. <br /><br />Last time out (yesterday) even with the rear transom cushion/cover off (it rotted away so I just scrapped it) the pinging was barely noticable, but still happened after a few minutes of running. Again, the slightest throttling back stops it. <br /><br />Now, I think that this is probably all due to the gas that sat in the tank before I bought the boat, and over the winter, losing it's octane rating. This is backed by the fact that as I add more new 89 octane gas the problem gets less and less noticable. I just want to bounce it off you guys to see what you think. <br /><br />My next step is going to be to run the tank almost empty, then fill with 93 octane. Hopefully this will take care of it once and for all.

 

[Fishermark]

Re: Quick Sanity Check Here - Pinging

Sounds reasonable. Instead of waiting to run the old gas out, why not add a can of octane booster to your present gas?

 

[TwoBallScrewBall]

Re: Quick Sanity Check Here - Pinging

I was thinking about that too. Might try it while this tank is running dry.

 

[crazy charlie]

Re: Quick Sanity Check Here - Pinging

When you say "new engine" do you mean new new and not broken in ??????Charlie

 

[TwoBallScrewBall]

Re: Quick Sanity Check Here - Pinging

I broke in the cam on the trailer, ran 25 minutes at 1500RPM. I spent the first day on the water finishing the actual break-in. Forgot to mention that. Typical procedure, varied RPM, small bursts of WOT, so I didn't get the pinging then. <br /><br />I only first heard the pinging when I was doing top speed tests trying out props for WOT RPM. <br /><br />I'm editing the post above. There was a tank of gas I used for break-in after the 3 gallon fill-up, that I forgot all about, I think I used 12 gallons.<br /><br />Why do you ask?

 

[LubeDude]

Re: Quick Sanity Check Here - Pinging

I think you have it figured out providing you have the timing set properly. Did you have to have the head shaved when you did the rebuild? If soo, how much? If 20 thousands or more, you will probably have to run 93 from now on, or get a thicker head gasket.

 

[TwoBallScrewBall]

Re: Quick Sanity Check Here - Pinging

Wasn't a rebuild, it is a 2002 long block. I'm going out on it tonight, I'm going to try octane booster today and see what happens. I'm sure the timing is dead on now. First time, I set it in direct sunlight and had a hell of a time seeing the mark consistently. Second time it was evening and there was no doubt about it.