Did I cause my HG to blow?

[LucasEnglish]

I bought my '93 6.5turbo from my dad a few months ago. He bought it new in '93. In '96 at around 50k the HG blew very bad. Big smoke show. He did not overheat the truck- it just went. The dealer fixed it under the motor warranty.

Since I have had the truck I have done a few mods. High flow air filter, 3.5in DP with straight 4in and a helper spring on the Wg. I also have a boost and EGT gauge pre turbo. A month ago I put a helper spring on the WG. This brought the egt's down by 200deg. No load WOT into OD the boost is between 7-10psi. Once in OD or pulling a load it will climb to 14psi. Egt's never get over 800deg. Last week I turned the inj pump timing up moved it about 1 line past the factory line. Did not notice much power gain, but did bring the egt's down 100deg.

Well, here is my Qustion and problem.I was on a 600mi trip this week and after about 400mi the HG started to go. I could hear the rad cap making noise and the coolent resevoir was bubbling like a volcano. It pushed the resevoir about 80% full and stopped there but still bubbling like crazy. The truck never got hot and I drove the 200mi home. If I let all the pressure out and put the cap back on and rev the truck 2-3times the coolent lines get rock hard and start to pop the cap. So this truck now has 100k on it, so it has gone around 50k on current HG. Do you guys think advancing timing could have caused the gasket to go out or is it just a coincidence? I will be taking the heads off tomorrow. Should I get factory gaskets or aftermarket of some kind? Anything special I can do to make sure they don't blow again besides lower comp pistons?

Sorry for the stupid newbe questions the archives just did not have much about inj timing and the effects or much about HG problems.

[DogDiesel]

I have done hundreds of headgaskets on 6.2s and 6.5s.
6.2/6.5 Headgaskets fail because of heat. When the coolant system works, and it adequately takes heat away from the head area, they last forever, but (sometimes with no regard for what gages say) when they fail, look for coolant problems.
Could be fan clutch, could be rad cap, somewhere pressure is coming out, or it was pulling more than the cooling system would cool. Something amiss.
Sure, if the timing is off, the engine is not effient, and unwanted heat is made.
Fix it, don't drive on, pressurize the coolant system, check for leaks enjoy the engine. Parts are reasonable. BTW- invest in new headbolts.
Wayne

[catmandoo]

yes definately new head bolts. about 16 years ago in my dads shop we put headgaskets in an olds 5.7 diesel and after work were setting around havin a few beers and we here this ping come from this car. so we look around and finally find the cause. one of the headbolts popped the head right off so from then on i have always used new bolts.

[LucasEnglish]

The truck has got hot in the past not over heating, but the stock fan will not kick in till almsot 240deg. Has done this its whole life. I will be geting a after markit fan clutch this week. Just doing most of my EX work and the boost. She hardly ever gets over 210 any more. The truck is being taken apart today.

[billg]

Diesel Dog,
I have a 93 and have noticed my coolant recovery tank almost to the top on several occasions while hauling a camper. No obvious bubbling or super stiff hoses, yet. My question to you is, in your experience, did you find it was just the head caskets or were the heads cracked as well? As a precaution do you just sleeve the heads regardless? I

[DogDiesel]

It is not unusual to see cracked heads, in the combustion area. Cracks visible to the naked eye, and between valves.
While a concern, if the cracks do not reach a coolant jacket, and most times they do not, they are just there. Hairline cracks. That judgment call will usually catch you at the machine shop.

I need one more anyway. smile.gif I have one as a weight for the bush-N-bog harrow on my compact diesel, on just one side. I need a matching weight for the other side. Makes it dig deep. ;)
Wayne