I recently changed my engine because my 599 block had cracked starter mount. Bought the truck and I didn't know the guy welded a stud in for the starter. Anyhow put in a supposedly low hour hummer 6.5 engine. Installed new cable for relocation kit. But the engine cranks a long time before it starts. I set my wastegate 5-6lbs with a pull scale. When it does start it runs smooth but ya pull out and it will stall out and won't start again. New PMD already lift pump comes on with key but the computer wont talk to my otc genisis scan. Keeps saying no data. Also seems to have excessive blow by. I did have it running in the garage for about 4 hrs hoping the blowby would settle.
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6.5 navistar 506 blowby
- Thread starter Dunk123
- Start date
"Anyhow put in a supposedly low hour hummer 6.5 engine..."
1) Any warranty on the used engine?
Blow by indicates a cracked piston if it huffs. Steady blowby means they got the rings hot and they lost their temper. This engine will need to be re-ringed. May as well check the cam bearings while it's back out.
I have had luck with CUCV engines, but, zero luck with burned out 6.2 Hummer engines.
Long crank time
1) Check for air in the fuel system. Aka use a clear hose on the IP return.
2) What is the cranking RPM? If it doesn't meet min crank speed because of bad battery, cables, or starter you will have non-stop no-start problems.
3) A compression test is a good idea... One YOU do not the supplier.
1) Any warranty on the used engine?
Blow by indicates a cracked piston if it huffs. Steady blowby means they got the rings hot and they lost their temper. This engine will need to be re-ringed. May as well check the cam bearings while it's back out.
I have had luck with CUCV engines, but, zero luck with burned out 6.2 Hummer engines.
Long crank time
1) Check for air in the fuel system. Aka use a clear hose on the IP return.
2) What is the cranking RPM? If it doesn't meet min crank speed because of bad battery, cables, or starter you will have non-stop no-start problems.
3) A compression test is a good idea... One YOU do not the supplier.
This is just my opinion on the subject so take it as that....
Their is no such thing as a "low hour" hummer motor, it was removed for a reason, they aren't removed for any other reason other than it isn't trustworthy any longer, the military treats them as expendable and they are just that..
Any take out motor needs rebuilding for a assortment of reasons, these motors are cheap assembly line motors, no warranty and built that way.
If you have blowby you have something bad or going bad, if rings are wore out it's not a low hour motor by a long way...
Take a video of the blowby, post it to utube then post a link here for us to see and hear...
Their is no such thing as a "low hour" hummer motor, it was removed for a reason, they aren't removed for any other reason other than it isn't trustworthy any longer, the military treats them as expendable and they are just that..
Any take out motor needs rebuilding for a assortment of reasons, these motors are cheap assembly line motors, no warranty and built that way.
If you have blowby you have something bad or going bad, if rings are wore out it's not a low hour motor by a long way...
Take a video of the blowby, post it to utube then post a link here for us to see and hear...
Been running the truck. It used 1gallon of oil to one tank of fuel. I did add a quart of ATF to see if the rings were maybe stuck causing the blow by. Checking compression this week. Also is it possible for turbo seals to cause this. It's a shame this truck runs great now except for the 30:1 fuel to oil ratio
Will L.
Well-Known Member
Did you do the clear air line off ip return to verify no air intrusion?
Do a compression test AND then a cylinder leak down test on all cylinders, writing info on each cylinder as you go.
Did you reset timing after installing your ip onto the hummer take out? what is desired and actual? Are you using that "new" ip?
what is rpm while cranking?
Was the Hummer engine Hummer or Hmmwv:
Did you reuse your injectors or put in a set of new turbo injectors. If you reused the hmmwv injectors, that isn't helping the starting issues. If Hummer where did you get it?
The above comments are on point. Opening it up for new rings and bearings is usually a good idea. I know there are some honest low mileage hummer take outs. Many hummer owners simply aren't happy with the power and drop in hopped up dmax or cummins.
IF hmmwv vs hummer, your chances of getting a pristine take out dramatically falls.
Do a compression test AND then a cylinder leak down test on all cylinders, writing info on each cylinder as you go.
Did you reset timing after installing your ip onto the hummer take out? what is desired and actual? Are you using that "new" ip?
what is rpm while cranking?
Was the Hummer engine Hummer or Hmmwv:
Did you reuse your injectors or put in a set of new turbo injectors. If you reused the hmmwv injectors, that isn't helping the starting issues. If Hummer where did you get it?
The above comments are on point. Opening it up for new rings and bearings is usually a good idea. I know there are some honest low mileage hummer take outs. Many hummer owners simply aren't happy with the power and drop in hopped up dmax or cummins.
IF hmmwv vs hummer, your chances of getting a pristine take out dramatically falls.
You had better come up to speed on "crankcase oil fed Diesel engine RUN AWAY" PDQ because your and other's lives may depend on it. Hint when the engine is revving to the moon the safest place to be is behind it or in front of it. NEVER on the sides of a runaway diesel. And after it finally comes to a stop be warned the cooling system can literally explode a couple min later.
1 Quart every 500 miles in Extreme use is normal. Otherwise IMO you are one step away from this engine running away on it's own oil.
How much oil is the CDR pumping into the turbo from blow by? You need to check the turbo for oil being thrown in the engine ESP from high crankcase pressure overcoming the turbo seals.
Bluntly you got burned on this engine, now PARK IT and FIX IT before it runs away and kills someone!
1 Quart every 500 miles in Extreme use is normal. Otherwise IMO you are one step away from this engine running away on it's own oil.
How much oil is the CDR pumping into the turbo from blow by? You need to check the turbo for oil being thrown in the engine ESP from high crankcase pressure overcoming the turbo seals.
Bluntly you got burned on this engine, now PARK IT and FIX IT before it runs away and kills someone!
MrMarty51
Well-Known Member
Engine in My truck was using some oil, dont rightly remember the exact amount, two qts in 3000 miles I suppose. I installed aa new CDR and oil consumption dropped to a half quart in 3000.
Will L.
Well-Known Member
My biggest question Didn’t answer, so:
Is this a military take out that came from a HMMWV, or a civilian HUMMER take out for engine swap?
If HUMMER, Where did you get it? I ask because it is possible to track the owner and discover details.
You can yank and rebuild this engine. How much you want to spend and what are your expectations would come into play. But it is possible you have an engine that could run a long time without rebuilding, but you need to do the diagnostics first. They should be done before tearing down the engine anyway unless you plan on a high dollar completely perfect rebuild like New heads or having yours completely rebuilt as if there is issue. Also new injectors or having yours rebuilt.
Your budget and use are critical.
There are guys on the Hummer forum that decided on $15,000-$20,000 new 6.5 engine after labor just to ensure their toy will work on the 4 weekends per year they use it. May never break 2,000 miles per year. Others put on more miles than a taxi. Someone with that low of use shouldn’t bother with upgrades like timing gear drive, balancing the engine internally, upgraded balancer and pulley, etc. But anyone using it as daily driver and wanting 200,000+ miles absolutely should do that and more.
If this pickup is an occasional use item- haul stuff on projects and therefore low mileage, just a back up vehicle, wanted a diesel truck just to see what your friends have one for- it may not be worth it to you for a high dollar investment here. If you're working this truck heavy and a lot of miles- a stock rebuilding of the engine may be the wrong choice. Lowering compression and bigger turbo with flowed heads, new intake and exhaust, upgraded tune, etc should all be determined before you rip anything apart.
The more we know the better we can help.
Is this a military take out that came from a HMMWV, or a civilian HUMMER take out for engine swap?
If HUMMER, Where did you get it? I ask because it is possible to track the owner and discover details.
You can yank and rebuild this engine. How much you want to spend and what are your expectations would come into play. But it is possible you have an engine that could run a long time without rebuilding, but you need to do the diagnostics first. They should be done before tearing down the engine anyway unless you plan on a high dollar completely perfect rebuild like New heads or having yours completely rebuilt as if there is issue. Also new injectors or having yours rebuilt.
Your budget and use are critical.
There are guys on the Hummer forum that decided on $15,000-$20,000 new 6.5 engine after labor just to ensure their toy will work on the 4 weekends per year they use it. May never break 2,000 miles per year. Others put on more miles than a taxi. Someone with that low of use shouldn’t bother with upgrades like timing gear drive, balancing the engine internally, upgraded balancer and pulley, etc. But anyone using it as daily driver and wanting 200,000+ miles absolutely should do that and more.
If this pickup is an occasional use item- haul stuff on projects and therefore low mileage, just a back up vehicle, wanted a diesel truck just to see what your friends have one for- it may not be worth it to you for a high dollar investment here. If you're working this truck heavy and a lot of miles- a stock rebuilding of the engine may be the wrong choice. Lowering compression and bigger turbo with flowed heads, new intake and exhaust, upgraded tune, etc should all be determined before you rip anything apart.
The more we know the better we can help.
MrMarty51
Well-Known Member
I would thoroughly enjoy sending My engine off to twisted Steel Performance and allow Him to pull His magic on it, injectors to Akdieseldriver to get balanced and a new uprated injection pump. Biggest problem with all of that, dont have a big enough CC and no means of paying it back if I did. LOLOLOL