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Daves71, ASE Certified Technician
Category: Chevy
Satisfied Customers: 719
Experience:  35+years experience in automotive repair
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94 6.5 TURBO DIESEL, NO START, spins..glow plugs..other cylinders

Resolved Question:

94 6.5 TURBO DIESEL, NO START, spins fast and only 180 lb. comp. Remove #1,#2 & #3 glow plugs and other cylinders will go up to 270 lb. comp. and cranking speed seems normal. Inspected timing chain, crankshaft OK..
Submitted: 8 years ago.
Category: Chevy
Expert:  Daves71 replied 8 years ago.
Hi lewis,do you have any smoke out of the exhaust while cranking or fuel out of the glow plug holes?Did this problem come on all at once or did it get hard to start and then got to the no start problem? Thanks,Dave
Customer: replied 8 years ago.
Truck run a little rough sometimes but came in as a no start. Did have smoke w/ cranking and fuel vapors from glow plug holes.
Expert:  Daves71 replied 8 years ago.
Are all the glow plugs good and is the glow plug system working?
Expert:  Daves71 replied 8 years ago.
Also early 6.5 cylinder heads were not GM's best products,have had more than a few that came through my machine shop with burnt valves and/or that were cracked.
Customer: replied 8 years ago.
Glow plugs & controller Ok and function Ok. I pressureized same cylinders with low compression and very minimal leakdown. I need to find cause of low compression and free spin w/ cranking with all glow plugs in. With 1,2 & 3 glow plugs out the other cylinders will make more compression and cranks with more resistance but never gets to 300+ lbs. compression. I suspected timing problem or broken crankshaft but found no problems there.
Expert:  Daves71 replied 8 years ago.
How about camshaft,pull valve covers and see if all rockers are moving,any bent pushrods? If you put 123 back in and take out 456 glow plugs what happens?
Expert:  Daves71 replied 8 years ago.
Got to thinking more about this overnight,the only things that can lower compression are poor piston ring seal,compression leaking by the valves and/or blown head gasket.I think in your case its a blown head gasket,thats why the rise in compression when you take the glow plugs out. Thanks, Dave
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Expert:  Daves71 replied 8 years ago.
If this answers your question please click ACCEPT as thats how we get paid. Thanks , Dave