No heat at idle LLY

[jimboagogo]

I have a customer with a 2004 K2500,4 door long box.He doesn't pull heavy with it but he has had it reprogramed and I'm sure he drives it hard with minium service.It has approx. 235,000 km(140-150K miles)on it.His low collant light came on so he was adding coolant to it 1-2 litres a month.So he took it to a shop on the other end of town and they put a water pump on it.He works construction with it so at break they sit in the truck and run it for heat.He doesn't get any heat unless he revs it up(say's he never used to have this problem before the water pump was changed).So he had the same shop change the T-stats still no heat.He brought it to me and it seems like it gets air locked.I blead it out and it is good for the day.It seems to burp when the t-stats open but it gets pretty hot if you watch the data stream on the scanner until they open,then you feel the fan sucking hot air through the rad and you instantly have heat.Now I'm thinking head gaskets maybe.I have done a lot of reading here about this problem and I couldn't figure out if the LLY has the same problem with injector cup's as the LB7 do.So I'm going to get the truck in next week and do the bubble check test and remove the glow plugs and check for coolant.Any advise or info would be greatly appreciated. Jim

[More Power]

It sounds like the engine has a head gasket with a compression leak, that's leaking cylinder pressure into the cooling system. This sort of problem frequently results in leaking water pump seals because of the overpressure. Maybe that's why the wp was replaced....

Discovering which cylinder bank is leaking can sometimes be determined by removing all eight glow plugs after an overnight shutdown. Any glow plug with moisture on it would indicate a leak for that cyl.

Jim

[jimboagogo]

Can anyone tell me if there is still a possibillity of being a leaky injector cup/seal on an LLY?

[Rabbler]

I don't think so.
I'm pretty sure the injector cup is permanently pressed in the head on the LLY and later engines.

[jimboagogo]

If I can figure out how to post pics I want someone to tell me what these mark's are.Each cylinder has them and the pattern looks pretty much uniform.Also it is head gasket trouble.The fire ring on #7 was pretty erroded.I could feel a small groove in the head where the fire ring contacts so I'm have the head's skimmed.I hope this doesn't create any other issues,it has adjustable rockers so it shouldn't.As I stated earlier this truck has been re-programmed looking for better fuel mileage so I am currious if the earlier timming contributes to gasket failure?My local GM dealer tells me there is an updated gasket for them so it might have nothing to do with the programming.Wow those return lines are a rip-off.I broke one of the "T's" off so I figured I'd replace both sides.My cost on both is $417.00.Thats just rude they don't deserve any form of bail-out.It's a pretty big job,lot's of stuff to remove or just move.But all in all it hasn't been too bad(way better than head gasket's on a 6.0L)Any tip's or advice from experienced voices would be listened to and appreciated. Jim

[Quack_Addict]

The marks are what they call "leopard spots" - perfectly normal. They are from an induction heat treatment of the cylinder walls. They only did this to the top 1/3 or 1/4 of the cylinders.

[hapaschold]

jimbo

i noticed parts prices on alot of things i fix at work have gone up 5 xs...
think manufacturers are making up for loses in sales.



2 3/4 teflon orings....last year 3.80....now 19.97
the diaphrams for the air pumps..... set of 4 pcs used to be 99 bucks...now 503 bucks..
thanks ingersoll rand ! !

[madmatt]

Be sure to torque everything under the valve covers. Seen too many come in the shop after a independent shop did injector or head gaskets with loose or overtightened return lines leaking.