Bad Cylinder head or gasket?

Rob · April 04, 2010, 09:59:46 AM

Last year I found the plug in cylinder # 6 fouled, so I cleaned it up and I started running much better. Then I started to notice that I was losing coolant, and was begining to overheat at idle. Additionally, I started blowing alot of white smoke out of the right side exhaust once the car is warmed up. I do not have water in my oil, or oil in my water,. I am guessing that I either have a leaking gasket, or a crack in the head around the # 6 cylinder combustion chamber causing coolant to leak into the compression chamber, but not into the bottom of the engine. Based on everyones experience here, am I on the right track? Obviously I'm pulling the right cylinder head; does that sound more like a gasket, or a cracked head, and is there anything else that I might be overlooking as a cause.

Thanks!

Rob · April 04, 2010, 10:07:04 AM

Forgot to mention it's a "75 350, and the only thing different that I did last year was go to 16 lb rad cap from the 7 lb I was using

UGLY OLDS · April 04, 2010, 02:03:28 PM

Before teardown, can you do a leak down test on the #6 cylinder & watch for bubbles in the radiator??? That will help narrow it down.....

Bob...........

wayne petty · April 04, 2010, 06:26:52 PM

better than a 50 percent chance of a cracked head on a 75 motor...

you might want to pick up a set of already done heads first.. a head gasket set... a tube of hylomar.. a 7/16-14 bottoming tap.. one of the 10 way scrapers..

this way.. you can just rip it apart... clean the decks... tap the threads.. and get it back together in just a few days.. and control the costs..

valve grind. magnaflux .. valve guides.. hard seats.. new valves.. new stock springs.. all add up... it all depends on how much time you have and if you plan on doing a lot of the valve grinding your self.. new SBC valves are cheep... usually under 8 bucks each.. if you shop around..

or spending the time its apart... do to a little port and polishing.. but this can be done on the replacement heads also.. if you don't nick a valve seat..

so many options.. but the Hylomar is not an option.. it will save you later...

Rob · April 04, 2010, 09:23:36 PM

Quote from: "wayne petty"better than a 50 percent chance of a cracked head on a 75 motor...

you might want to pick up a set of already done heads first.. a head gasket set... a tube of hylomar.. a 7/16-14 bottoming tap.. one of the 10 way scrapers..

this way.. you can just rip it apart... clean the decks... tap the threads.. and get it back together in just a few days.. and control the costs..

valve grind. magnaflux .. valve guides.. hard seats.. new valves.. new stock springs.. all add up... it all depends on how much time you have and if you plan on doing a lot of the valve grinding your self.. new SBC valves are cheep... usually under 8 bucks each.. if you shop around..

or spending the time its apart... do to a little port and polishing.. but this can be done on the replacement heads also.. if you don't nick a valve seat..

so many options.. but the Hylomar is not an option.. it will save you later...

Thanks for the info; I assume the Hylomar you refer to is the sealant, which one is best? There's a few on their website. I've never heard of or used it before.

wayne petty · April 04, 2010, 10:09:16 PM

i have used the permatex version .

that seems to be the Hylomar® Advanced Formula

i got a half dozen when AZ /permatex discontinued it..i dont have a clue where they are stashed... i have gotten it through goodson.com ordered through a machine shop i deal with... but it looks like they only sell it with a pint or quart of solvent now.. perhaps in the main catalog..

you do have to let the hylomar air out 15 minutes after you spread it on the gasket.. hanging in the air... before laying on the gasket and the head.. its not going to dry... just to let any solvents evaporate out..

Rob · April 05, 2010, 12:49:24 PM

Quote from: "wayne petty"i have used the permatex version .

that seems to be the Hylomar® Advanced Formula

i got a half dozen when AZ /permatex discontinued it..i dont have a clue where they are stashed... i have gotten it through goodson.com ordered through a machine shop i deal with... but it looks like they only sell it with a pint or quart of solvent now.. perhaps in the main catalog..

you do have to let the hylomar air out 15 minutes after you spread it on the gasket.. hanging in the air... before laying on the gasket and the head.. its not going to dry... just to let any solvents evaporate out..

Gasket seems fine, must be the head (sigh!) Nicked the fender when romoving the head (double sigh) Now I gotta decide whether to find a set in a bone yard, or go aftermarket......

Either way, I won't be crusing for a while ($$$)

Thanks for all the advise

wayne petty · April 05, 2010, 01:00:25 PM

wire brush the areas between the valves.... the crack if its there will be between the seats... or though a seat off at a 45 degree angle..

38HAULR · April 05, 2010, 08:15:04 PM

Had similar, many moons ago with a rebuilt 283.
Developed rough idle,and chucked white smoke from the LH tail pipe on the twin system.
I fired her up cold, ran and shut down and found ,pressure release when the rad cap was pulled. and one plug with moisture crystals from the offending bank.
Replaced both head gaskets and she was fine after that.
I might add that the gaskets that I originally used were the metal items,this time I used the composition gaskets.
Frank.

wayne petty · April 07, 2010, 10:46:18 AM

rob.,....

got pictures?

of the chamber side of the heads...

and high res of the gaskets even if you have to take 4 pictures of each gasket so we can examine them for leakage...

the ability to read the sealing areas of a gasket is learned...

did you blow all or any coolant out of the cylinders... replacing it with wd 40 so the cylinder walls and piston rings don't rust while you are waiting???

i feel bad about the fender scratch.. i did that only one time.. decades ago. to a freshly painted firemist green metalic 63 cad eldorado convertible.. the boss was in.. and the new owner was about to pick up... thank goodness we had a professional painter on staff...

i still cringe just thinking about it...

Rob · April 07, 2010, 01:57:05 PM

Quote from: "wayne petty"rob.,....

got pictures? of the chamber side of the heads...

and high res of the gaskets even if you have to take 4 pictures of each gasket so we can examine them for leakage...

the ability to read the sealing areas of a gasket is learned...

did you blow all or any coolant out of the cylinders... replacing it with wd 40 so the cylinder walls and piston rings don't rust while you are waiting???

i feel bad about the fender scratch.. i did that only one time.. decades ago. to a freshly painted firemist green metalic 63 cad eldorado convertible.. the boss was in.. and the new owner was about to pick up... thank goodness we had a professional painter on staff...

i still cringe just thinking about it...

I just dropped the head off at the machine shop. Nothing obvious with the gasket, the # 6 combustion chamber was pretty fouled with what looks like oil residue, not clean as I would have expected if coolant was getting in. Never thought about taking pictures, that would have been a smart move! The piston was caked too. The exhaust valve in # 4 is white, with no carbon build up, the other valves looked OK. There was a fair amount of carbon/oil build up in the exhaust ports of # 6 and #4. The guy at the machine shop is still suspicious that the gasket may be the problem, although it looks like some over-heating is occurring by the #4 & 6 plugs. The oil in the # 6 combustion chamber makes me wonder if a ring is letting go(?) Depending on the results of the cylinder head inspection/testing, I may end up pulling the piston to see if that is a problem, although I am not burning oil at all.
The only coolant on the piston was what spilled out when I pulled the head, and interestingly, there was oil on top of the piston, but virtually no carbon build up, mopping up the coolant also cleaned the top of the piston. I assume normal carbon build up would not come off that easily. I will hit the walls with WD 40 though, thanks for reminding me!
The paint damage is limited to the top of the fender by the drivers side, it's basically a deep chip by the hood side (37 chev). I can touch it up and it shouldn't be too obvious. At this rate, it's not going anywhere for a while, so I have some time on my hands to look after these issues.
I'll let you know what the machine shop finds (or doesn't find), but the combination of symptoms has everyone stumped so far, so I don't feel to stupid.

Thanks!

wayne petty · April 07, 2010, 05:05:12 PM

before the trash goes out.. grab the intake manifold gaskets... if they came off in mostly one piece... look at how much crush there was on the top and the bottom... perhaps you can see if it was leaking coolant ... or leaking vacuum from the lifter galley side of the intake..

look at the faces of the intake manifold mating surface.. see if you can read it..

there is a sure fire test.. that i was going to post.. but had distractions...

compressed air... a compression tester hose that can hook to the air hose.. take the valve core out of the end of the compression tester hose.. take out one spark plug at a time.. use a remote starter switch with the hose screwed into the hole.. to bump the engine around till you get each cylinder to TDC.. charge the cylinder with full shop air pressure.. warning .. the motor might turn.. you also might want to block open the carb or throttle body ... do this with the radiator cap off and the cooling system topped ... see if the coolant rises with the compressed air in the cylinder..

if it does.. you have found a leak...

i have seen some.. mostly v8 fords.. that blew the head gasket out but did not loose coolant..

do this with only one spark plug out at a time...

if the motor spins over.. just reset with the remote starter switch..

i am sorry that i left the barn door open and let your horse out before you tied him up... (head off before this test) i do try to include enough information .. but i never know who has read my posts.. and who has not.. i know i posted this test last week.. here?

i take it that you know how to put a distributer in with the engine moved from where it was...

why not bump the engine around and check the cylinder walls..

i wish there was another way to check ring sealing..

perhaps a clear plastic O ring sealed round cap that one could bolt down with hold down machine clamps on top of the cylinder.. this way... you could seal the bore.. and test the sealing of the piston rings.. with compressed air and a leak down gauge.. or a vacuum pump.. this might be really handy... anybody got some scrap plastic.. and a lathe to cut it into a 5 inch round blank.. machine an oring groove for a 4 and a quarter ID oring.. a 14mmX1.25 hole.. perhaps hollowing out the cylinder side to clear pop up pistons..

think of cylinder head CC device.. but thicker..

i wish i had a lathe... and a mill... but i have fingers to do my talking with..

Rob · April 07, 2010, 06:14:43 PM

Quote from: "wayne petty"before the trash goes out.. grab the intake manifold gaskets... if they came off in mostly one piece... look at how much crush there was on the top and the bottom... perhaps you can see if it was leaking coolant ... or leaking vacuum from the lifter galley side of the intake..

look at the faces of the intake manifold mating surface.. see if you can read it..

there is a sure fire test.. that i was going to post.. but had distractions...

compressed air... a compression tester hose that can hook to the air hose.. take the valve core out of the end of the compression tester hose.. take out one spark plug at a time.. use a remote starter switch with the hose screwed into the hole.. to bump the engine around till you get each cylinder to TDC.. charge the cylinder with full shop air pressure.. warning .. the motor might turn.. you also might want to block open the carb or throttle body ... do this with the radiator cap off and the cooling system topped ... see if the coolant rises with the compressed air in the cylinder..

if it does.. you have found a leak...

i have seen some.. mostly v8 fords.. that blew the head gasket out but did not loose coolant..

do this with only one spark plug out at a time...

if the motor spins over.. just reset with the remote starter switch..

i am sorry that i left the barn door open and let your horse out before you tied him up... (head off before this test) i do try to include enough information .. but i never know who has read my posts.. and who has not.. i know i posted this test last week.. here?

i take it that you know how to put a distributer in with the engine moved from where it was...

why not bump the engine around and check the cylinder walls..

i wish there was another way to check ring sealing..

perhaps a clear plastic O ring sealed round cap that one could bolt down with hold down machine clamps on top of the cylinder.. this way... you could seal the bore.. and test the sealing of the piston rings.. with compressed air and a leak down gauge.. or a vacuum pump.. this might be really handy... anybody got some scrap plastic.. and a lathe to cut it into a 5 inch round blank.. machine an oring groove for a 4 and a quarter ID oring.. a 14mmX1.25 hole.. perhaps hollowing out the cylinder side to clear pop up pistons..

think of cylinder head CC device.. but thicker..

i wish i had a lathe... and a mill... but i have fingers to do my talking with..

Both intake gaskets are intact, I'll take a look at them now (they're still on the intake)....I'm back, no obvious problems with the gaskets but the one intake runner (is that the correct term?) red arrow (second pic) has what looks like the oily residue that is in the combustion chamber. The blue arrow shows build up, that is on both sides of the intake. The arrows are tough to see when I shrunk the pic down so it would upload

first pic is a closer view of the residue

wayne petty · April 07, 2010, 10:09:46 PM

i don't like the way they fit on the intake... notice the bottom of the intake port has a lot of metal showing..

got a brand and casting number from that intake...

how about the casting number from the heads

this way ... we can identify them to know what intake gaskets to use... there are variations..

the motor does have 4 inch pistons right?

??

what does anybody else think?

??

Rob · April 07, 2010, 10:35:06 PM

Quote from: "wayne petty"i don't like the way they fit on the intake... notice the bottom of the intake port has a lot of metal showing..

got a brand and casting number from that intake...

how about the casting number from the heads

this way ... we can identify them to know what intake gaskets to use... there are variations..

the motor does have 4 inch pistons right???

what does anybody else think???

"882" heads, the intake is Professional Products 52000 (basically, it's an Edelbrock knock-off) I don't remember the gasket not looking like tht when I installed it. I can see how that might lead to the oil residue, but the coolant too? Never had a problem with leaks.

Yes, 4" pistons