97 S big bolt block rebuild

[97-6.5TD-F]

Am in the process of buying a 97 K1500 that ran out of oil. I got the engine tore down to a bare block today, and to my glee I found no visible cracks in the main webs. The pistons look okay also, but i have some out of a GM long block that had only 10000 kms when the water the owner had in the cooling system popped the block open near the starter :eek: .

What I am concerned about are those small cracks on the heads in between the valves. It seems every 6.5 head I have taken off with any kind of milage has those cracks. Should I replace them?

One last question, I am considering the stud girdle kit and gear drive timing set. Any feed back on those? Thanks

[Robyn]

Howdy

The cracks in the main webs can be very hard to see.

Wash the main webs down (center three) with brake clean in the area between the outer bolt and the pan rail.

Wipe dry and then warm the areas one at a time with a propane torch.
You dont need to cook them but they need to be hot to the touch.

Once you have them good and warm, let them sit for a few minutes.
If there are any cracks there the oil that will have soaked into them will bubble out and show any cracks very well.

Do these one area at a time and warm both the front and back of the web area.

The cracks generally form in the center of the outer bolt hole and run toward the cylinders and slightly toward the pan rail on an angle.

I had a 599 block that looked very good and with the heat trick all the webs showed cracks. :(

Good luck and may you find your little prize healthy. :D

Keep us posted

Robyn

[john8662]

Sounds like the engine that through an interesting chain of events wound up in my '82 short box pickup.

You'll likely be turning the crank down .010 or finding a STD crank to use.

The '97 Big Bolt (outer main bolts) also had the LARGE oil spray cooler holes in the block and BIG Inside Diameter (ID) sprayer nozzles.

I'm pretty sure that GM offered an updated nozzle for these blocks that had a smaller ID nozzle to increase oil pressure in these engines. Mine has the big ones and one small nozzle (starting at the rear main), because i had to replace one.

Oil pressure will be greatly increased with the better spray nozzles, or just do as another builder told me and pinch them off, eliminating the spray cooling.

Mine idles at 6-9PSI fully hot (digital oil pressure gauge) :o

Which I found to be the norm with THIS block, you've been warned.

Stud Girdle?

Absolutly, no doubt in this block, luckily it's the more common version of the girdle kit.

J

[97-6.5TD-F]

Thanks to both of you, great info! But what I am really concerned about is if I have to buy some new heads for this thing or can I run them with those small cracks. I have heard that they dont matter, but I am very particular and dont like putting bad parts on a costly rebuild.

[MaxPF]

Assuming the head pressure tests ok you can repair the crack. Here's the link: http://www.thedieselpage.com/members/head.htm

[JeepSJ]

Where are you located? For a small fee (enough to cover the parts), you could stop by and use my KLine kit to put liners into the water jackets above the cracks.

[97-6.5TD-F]

Well I have the block honed, cam, lifters and crank in, DSG girdle bolted up, and gear drive timing set in place. Rings are in tomorrow so I should have the short block done on wednesday-thursday.

Now I just gotta figure out what to do for heads. Probably should just drop the 850 on a pair of complete new castings, i guess.

[97-6.5TD-F]

Oh yeah, anybody know what difference there is between F vin prechambers, versus my S vin ones? Thanks

[DmaxMaverick]

Oh yeah, anybody know what difference there is between F vin prechambers, versus my S vin ones? Thanks

F = Power
S = Economy

But, only a little give/take of either.

[mkhagemann]

there is a repair for those cracks that form between the valves. if you look on the intake side of the head you'll see four small plugs that locate the coolant passage between the valves. using a kit from Goodson.com (DCR-62-KIT) the hole is reamed slightly larger to accommodate a sleeve, then a larger plug to finish it off. The kits are $170.00, you might also check with your machine shop to do it as well. on another note, why would anyone want to pinch off the piston oil coolers for the sake of increasing idle oil pressure.

ASE Master Engine Builder
1995 C3500HD
1995 C7500
1996 C3500HD

[john8662]

on another note, why would anyone want to pinch off the piston oil coolers for the sake of increasing idle oil pressure.

This mainly applies to the early oil spray blocks that have too large of an ID on the nozzle, the oil pressure suffers greatly on these blocks.

Normal oil pressure has been noted to 6-9psi at HOT idle with the correct HV oil pump and perfect bearing clearances. My engine is NOT the only one to do this either.

A nonspray block with standard oil pump (82-96 6.2 and 6.5 pump) will HOT idle 25psi or better, so there is a difference.

Just a simple solution to a provision that created more problems than it solved.

The later blocks 98 and up used a smaller ID, and then later to a smaller OD on the nozzle bore into the block.

An enhanced block with small squirters would be just fine, no need to block them off.

J

[97-6.5TD-F]

Well its done, running and I have about 70 miles on it so far. She runs great with decent power!! My block did have the large spray nozzles and the pressure is kinda low at idle, but it dosent knock or anything so its fine by me!

Also I think those spayers are neccessary on these engines as the wristpins get there lube from a tapered hole on top of the con-rod small end.

[JeepSJ]

Also I think those spayers are neccessary on these engines as the wristpins get there lube from a tapered hole on top of the con-rod small end.

Lots of engines get their wrist-pins oiled that way, and they don't have sprayers. There is a lot of oil that gets spalshed up there as the crank spins.