smitty89

Hello guys. I was glad to find your board and I am thankful for any help you can give me. I just bought an 89 reg cab 2 wheel drive 4 speed truck from a friend. He had just finished putting a new top end on it for his son when his son got a different truck. It blew a head gasket and to get the head flat they milled it 10 thou. the problem is that i keep getting a pre ignition pinging. ive rolled the timing back to 4 degrees and is alot quieter and today it seemed to come and go. Could this be the hydraulic tensioner not working? also when i went to move the timing it was at 21 degrees instead of the 10 he set it at could the chain have jumped or has the milled head given it too much compression. it has lots of power but the mileage sucks so i'm left scratching my head. Thanks. Smitty

smitty89

Also I should note after reading some other threads that the egr valve was replaced just before the pinging started come to think of it, how could this affect it, bad valve, gasket?

jerryp58

I'm not sure if it would be significant or not, but milling the head will raise the compression ratio. What octane gasoline are you running?

Have you done a compression check to make sure the gasket sealed well?

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Jerry
2004 Frontier, King Cab, XE, 4x1, 4-cyl, 5-spd

smitty89

Yep the gasket is sealed good. I tried 91 octane and didn't make a difference. I live in calgary canada and right now in the morning it is about -8 celsius so its not a temp thing. I rolled the timing back to 1-2 degrees and it would still knock a little but it was not driveable like that so i put it to 4. Funny though when i bought it 3 weeks ago it did not ping otherwise i may have not bought it. but a day after i bought it it was almost undriveable it would chug and stall when pulling away from a light it had already new plugs wires cap etc so my friend who i bought it from had it fixed at a shop cause he felt responsible and they put in a new egr valve. And the more i keep thinkin about it it has pinged since they put it in, so iwas wonderin what the signifigance of that is? i should note that the muffler is very bad and it is getting loud i will fix that first before any more mods on the timing but I doubt that could be responsible right?