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Db2 swapped 6.5 refuses to run right

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Overthedge21

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Got recommended to this forum for some help on my issue. I picked up an 87 K30 a few months back with a blown 6.2 in it. Thing ran great with the exception of a cylinder that wouldn't fire due to a bad piston and cylinder bore. So I pulled it and took the pump and accessories off and scrapped the block. According to the 6.5 db2 conversion manual I found on here, it's supposed to just be a straight forward pump for pump swap. So I picked up a cheap 97+ 6.5 that got pulled for a bad DS4. Did a compression check and got a low of 350-370 psi on one or two cylinders, all the rest were up around 420, which I think is enough to run on all 8 right? Or am I stupid and is this the basis of my issue? Anyway, with the engine up onna home made test stand I stripped it down, pulled the heads and inspected the cylinders, put in new head gaskets and dropped in a set of ARP studs. Swapped the db2 onto it, times it all according to the timing marks, and haven't once been able to get it to run nicely. I'll attach a link to a video of it, the only way I was even able to get it to run like that was to advance the pump drive gear 2 teeth on the cam gear, thing wouldnt even start when the dots were lined up. This is as close to good running as I can get it, looking to see if anyone has any ideas. I plan on swapping in a cummins eventually for power and reliability since it's gonna be service truck/tow rig, but I wanted the 6.5 for now as a an easy drop in replacement to get it on the road and slowly collect parts for a swap maybe next year. So if anyone has any ideas I'm open to them, cuz I'm drawing a blank here
 
Well for starters, it's a very bad idea to run these without water even for 30 seconds, they create so much heat it's bad on head gaskets, but anyway...

Swap injectors around and see if that smoke in # 1 cyl follows ...

The timing sounds very advanced in the video.. the motor seems to have a lot of rattle...

Did you hear the motor run before you started this swap ?

It looks like smoke is puffing out of the vront water passage in the head, is it or just some steam ?
 
I agree with above.
Ssoooo advanced. How did you time it?

also the rule is 10% on compression tests. 10% down from stock is out of tolerance. Also a difference of 10% from highest to lowest- so... yeah... Lemme guess which 2 are lower- 7&8? It won’t run really smooth with that compression difference but it should be better than that.
 
Just steam coming out. Never heard it run before. I'll try moving the injector to another cylinder. I timed it with cylinder 1 at TDC and then spun it over and lined the pump gear dot to the cam gear dot. Didn't know that about the differences in compression. That this point I don't care if it heats up the head gasket, I'm one the verge of tossing this engine in the scrap pile anyway so that's the least of my concerns haha. It is quite advanced in the video but that's the only way I could get it to fire on more than like 3 cylinders
 
Welcome. You weren't getting good answers elsewhere.

The video sounds bad like it's knocking on one hole. Stuck injector, broken valve spring under the cap, debris, bad bearing... What does it sound like just cranking?

The 6.5 is simply a punched out 6.2, period. The (heads) injector angles change to clear the turbo better, single piece oil seal, different oil cooler line sizes... However the timing set and all bolt ons are the same. There is a chain spray shield for the CDR system that attached to the oil fill: but no other changes. BIG SHOW STOPPER: the V belts in 1987 use a different water pump backing plate due to the newer reverse water pump and fan rotation of the single serp belt system. Use the proper backing plate and water pump.

I have run several 6.2's in place of blown all to hell 6.5's including a DS4 on a 6.2...

Generally you fill the block with water so you can see if you get bubbles coming out either head port in the water/coolant. Cold engine. This makes sure the heads and gaskets are ok. From the video IMO it's not 100% steam it looks like a head gasket's blown. I would plug the water pump and fill the block with water before running it to do this bubble test. 2 min running idle is about all I would do with no water pump.

Does this engine have a new timing chain on it? IMO you have eroded a keyway if it needs that much advance off the timing marks to fire. You may not have purged the air in the fuel system before you advanced the timing trying to start it. Pull glow plugs, crank 30 sec at a time with 2 min to cool the starter till you get a mist out the holes. (This is at the end of this thread as well as the keyway erosion.)

1992 6.5TD Rescue

I have used tractor loader and ratchet strap, now I use a body shop lol
www.thetruckstop.us

How many miles on the injectors? They are done at 100K and the Commie China krap is done at 30K miles. Genuine Bosch rebuilds, or nozzles if you roll your own, not the low bidder.

What did you seal the studs in the block with? Fix it before you drop it in... :facepalm:

Head studs - what will stop the leak

After speaking and Emailing with Permatex: Best: Optimum Black -27037 #2: The Right Stuff (black) #3: Ultimate Black #4: Optimum Grey #5: The Right Stuff (grey) #6: Ultimate Grey There is one other possible option, but it has not been properly tested, even by Permatex for it- Seal & Lock...
www.thetruckstop.us
 
Sealed the studs with a high heat permatex that was recommended to me. Fuel system is well and purged, cranking it tosses plenty of fuel most out the exhaust ports. The keys all looked good when I had the timing assembly apart, the chain has a little slack but not much, unfortunately I'm not sure of the mileage on it. Could you enlighten me on the difference between the water pump backing plates? I see the pump has a weird little piece in the center of the shaft that sticks out into the timing case and gets pressed in against some type of spring pressure by the water pump plate, I've been wondering what it is. I can't remember which plate is which now, I've had 3 Detroits through here so parts have been hard to keep track of what came from where
 
It will be good luck if the injector is bad.
the 7th cylinder did not work for me until it heats up above 100F(40C). white smoke and bad sound. I changed the injector, hydraulic lifters, nothing helped.
As it turned out later, I had a bent connecting rod, I changed the piston and connecting rod, and everything became fine.

Tlime for new piston?

Measure bore. 102.98 mm in top bore 103.04 mm inside bore min and 103.08 max. Ellipse 0.04 mm Cylinder wear 0.1 mm Is it time to grind the block?
www.thetruckstop.us
 
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Water pumps only line up with the proper backing plate. You still using V belts or switching over to a serp belt? One is normal rotation and the other reverse rotation. If you have the setup off the '87 Pump, fan, etc. and are staying with V belts you are fine. This is the only gotcha change made.

New chains are cheap and you are looking at it... They stretch out in 30K miles due to the IP shock loads. If the aftermarket gear set is available it's a good investment. The book calls for a timing adjustment every 6 months due to the cheap chain. GM used an enormous slop spec of 0.8" but you beat the exhaust valve tips up before you get 0.8".
 
the timming for the db2 IP sounds off. I had similar issue when searching threads here for correct timming and the db2 and ds IP both are differant with timming. for the db2 first falling crank sproket with cam sproket at zeros instal Ip drive gear and rotate the engine 180 clock wise. the mark on the iPdrive gear should be straight up then install the IPgear the key on the IPshould be in between 7 and 6 o'clock poss. the key on IP should also along with the mark on gear assuming u have the origonal gear for the IP
 
also its not good to fire the engine without coolant PEWRIOD. extreme engine temps from hot to cold can easily screw your gaskets up
 
also on the db2 to advance timming the IP moves to the PASS. side not the drivers side .
 
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