165HP Inline Sixes - Detonation on hot starts only.

[Fordiesel69]

I have two inline sixes. One in my glastron, and one parts engine with cracked block. Both do the same thing. Once completely up to operating temp, both will crank and lock (detonate) each compression until they eventually fire up. Timing is good and they both run excellent without any pinging when running. Starters & batterys are newer and test good. Batteries are known good. Battery cables are also known good. Absolutly no water intrusion into cylinders causing hyrolock. And most importantly, they are cooling correctly.

I have ruled it out to be ignition system related, but have no clue how to fix. If I pull the coil wire, they roll over perfect when hot. Any ideas? I can post a video of this if need be.

 

[dan t.]

Re: 165HP Inline Sixes - Detonation on hot starts only.

Sounds to me like the balancer is slipped so what appears to be correct timing is actually advanced.Google "piston stop" to get an explanation of how to find true tdc. Or, compare the spacing between the keyway and the timing mark on a known good balancer with yours.

 

[Bondo]

Re: 165HP Inline Sixes - Detonation on hot starts only.

I have ruled it out to be ignition system related, but have no clue how to fix. If I pull the coil wire, they roll over perfect when hot.

Ayuh,... That says it IS an ignition problem...

 

[Fordiesel69]

Re: 165HP Inline Sixes - Detonation on hot starts only.

This is my spare parts engine demonstrating the detonation, my glastron does the exact same.

http://www.youtube.com/watch?v=2lrrc9JTmQI

Where I am confused, is if I run 87 octane and drive the boat under load, I do NOT get any ping or octane knock. Only on starts. If the timing was over advanced, would it not ping??????

 

[vxtech]

Re: 165HP Inline Sixes - Detonation on hot starts only.

replace battery cables