86 C30/350 head removal

tgzzzz · 04-20-2008, 07:46 AM

I have at least blown head gasket in my 86 C30/350 motorhome with 10K miles on rebuilt engine. It looks pretty tough to RnR head with engine in place. Should I bite the bullet and pull engine to do this job? I'm not an ace but have good help and air tools available.

Related issue: With engine running I had a LOT of oil vapor from hose to aircleaner to the point where oil was leaking out of cannister and dripping on engine. I then found that the smog pump belt was way loose. Tightening the belt made the engine run better immediately. Does that make sense? A mechanic opined that the oil vapor was blowby and thought the engine was a goner. I'm hoping the smog pump not working was the cause of the extreme vapor issue, and that all I have is a blown head gasket.

I drove engine about 100 miles with gradually decreasing power. Found water in two plugs (so far) and steam coming from one exhaust pipe. But rig still starts and runs reasonably well with 2 new plugs, I don't think it's a goner yet. Found brown residue in radiator overflow tank but no evidence of water in oil.

Thoughts?

zazlo · 04-20-2008, 08:32 AM

sounds like the head gskt or gskts are aproblem.you can help isolate this by removing the valve covers.turning the engine over by hand untill the suspect cylinder is at TDC [both valves closed] and introducing shop air into the cylinder,a leak down test.[100-150 psi is fine] .The cooling system will either build pressure[with the rad cap on] or with the rad cap off you may see bubbles in the rad.Watch for a cracked head when you isolate which cylinder[you can have them pressure tested at any compitant machine shop]the excessive blow by may be steam caused by water in the oil.The leak down test will also show you if the rings are an issue by bowing excessive air out of the crankcase.Look at the plugs when you pull them out the bad cylinder will be very clean or show sighns of coolant.If the leak is bad enough you can pressureize the cooling system for 15-20 min ,crank the engine over with the starter [ignition syst disabled]and watch for which hole blows out coolant.The cooling syst will have to be flushed ,Ive found using dish washer soap works well.[it cant make bubbles].You may have to do this numerous times

tgzzzz · 04-20-2008, 06:35 PM

Thanks.

The longer I look at things I realize I can get the head off without removing the engine.

gmctrucks · 04-20-2008, 08:50 PM

Buy new head bolts when putting the heads on this time. zazlo your the man good help.

leolkfrm · 04-21-2008, 04:57 AM

Yes you can get the head out we used to do it on the van bus version. Chances are the head is cracked between the valves, So anything you do will be a patch on an old engine that was rebuilt. If the coach is in nice shape and you are going to pull the engine put a goodwrench in it, not a rebuild! that way everrything is new and current.

tgzzzz · 04-22-2008, 05:45 AM

Thanks. I've been reluctant to start. Next week will tell the tale.

03chevy · 04-22-2008, 08:00 AM

i agree with gmstrucks new head bolts old ones get streched and do not torch out right!!

04-20-2008, 07:46 AM	#1
tgzzzz Full Member Join Date: Apr 2008 Posts: 18	86 C30/350 head removal I have at least blown head gasket in my 86 C30/350 motorhome with 10K miles on rebuilt engine. It looks pretty tough to RnR head with engine in place. Should I bite the bullet and pull engine to do this job? I'm not an ace but have good help and air tools available. Related issue: With engine running I had a LOT of oil vapor from hose to aircleaner to the point where oil was leaking out of cannister and dripping on engine. I then found that the smog pump belt was way loose. Tightening the belt made the engine run better immediately. Does that make sense? A mechanic opined that the oil vapor was blowby and thought the engine was a goner. I'm hoping the smog pump not working was the cause of the extreme vapor issue, and that all I have is a blown head gasket. I drove engine about 100 miles with gradually decreasing power. Found water in two plugs (so far) and steam coming from one exhaust pipe. But rig still starts and runs reasonably well with 2 new plugs, I don't think it's a goner yet. Found brown residue in radiator overflow tank but no evidence of water in oil. Thoughts?

04-22-2008, 08:00 AM	#7
03chevy Senior Member Join Date: Dec 2006 Location: jax,fl Posts: 1,185	i agree with gmstrucks new head bolts old ones get streched and do not torch out right!! __________________ A dirty mind is a terrible thing to waste!

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04-20-2008, 08:32 AM	#2
zazlo Full Member Join Date: Apr 2008 Location: vancouver bc Posts: 25	sounds like the head gskt or gskts are aproblem.you can help isolate this by removing the valve covers.turning the engine over by hand untill the suspect cylinder is at TDC [both valves closed] and introducing shop air into the cylinder,a leak down test.[100-150 psi is fine] .The cooling system will either build pressure[with the rad cap on] or with the rad cap off you may see bubbles in the rad.Watch for a cracked head when you isolate which cylinder[you can have them pressure tested at any compitant machine shop]the excessive blow by may be steam caused by water in the oil.The leak down test will also show you if the rings are an issue by bowing excessive air out of the crankcase.Look at the plugs when you pull them out the bad cylinder will be very clean or show sighns of coolant.If the leak is bad enough you can pressureize the cooling system for 15-20 min ,crank the engine over with the starter [ignition syst disabled]and watch for which hole blows out coolant.The cooling syst will have to be flushed ,Ive found using dish washer soap works well.[it cant make bubbles].You may have to do this numerous times

04-20-2008, 06:35 PM	#3
tgzzzz Full Member Join Date: Apr 2008 Posts: 18	Thanks. The longer I look at things I realize I can get the head off without removing the engine.

04-20-2008, 08:50 PM	#4
gmctrucks Senior Member Join Date: Nov 2006 Location: Houston,Texas Posts: 3,948	Buy new head bolts when putting the heads on this time. zazlo your the man good help.

04-21-2008, 04:57 AM	#5
leolkfrm Senior Member Join Date: Mar 2008 Location: N.Y. Posts: 4,225	Yes you can get the head out we used to do it on the van bus version. Chances are the head is cracked between the valves, So anything you do will be a patch on an old engine that was rebuilt. If the coach is in nice shape and you are going to pull the engine put a goodwrench in it, not a rebuild! that way everrything is new and current.

04-22-2008, 05:45 AM	#6
tgzzzz Full Member Join Date: Apr 2008 Posts: 18	Thanks. I've been reluctant to start. Next week will tell the tale.