Valve Stems Selas or Worse?

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palerider94

Member

Feb 21, 2006

573

1

19

Sep 17, 2007

#1

• Sep 17, 2007

• #1

Going to do a leakdown test this weekend but suspense is killing me. Car smpkes pretty good. Particuliarly at start up and heavy excelaration. After startup and normal driving not too bad. Has 70k original on 351c 4V. Sat for about 10 years until body restore. Runs pretty strong other wise. Hoping just selas - Any bets - seals, guides, rings?

 

enferno

Member

Jun 20, 2006

418

2

16

Sep 17, 2007

#2

• Sep 17, 2007

• #2

does it smell like oil?

could it be running rich?

 

TD68302

New Member

Jul 29, 2007

57

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Arvada, CO.

Sep 18, 2007

#3

• Sep 18, 2007

• #3

I would bet valve seals

 

JDS68Stang

New Member

Sep 3, 2007

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New York State

Sep 18, 2007

#4

• Sep 18, 2007

• #4

Could be all of the above, especially if it has set a long while. I had a 76 Monte Carlo that had the symptoms you descibe, I bought new seals, popped off the valve covers and the drain holes turned out to be clogged really bad. Cleaned them first, reinstalled the covers and she didn't smoke no more. Didn't need the seals after all.

Sticking rings I would try an additive first in the oil and run it real hard, take it up on the highway and wind it out about 4-5 times. I cured a Dodge vans sticking rings by doing this in the past as well. Other heavy smokers I wasn't so lucky with but these ideas have worked for me in the past with a few.

 

M

mikethebike

Member

Jun 12, 2007

358

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17

Greenville, SC

Sep 18, 2007

#5

• Sep 18, 2007

• #5

palerider94 said:

Going to do a leakdown test this weekend but suspense is killing me. Car smpkes pretty good. Particuliarly at start up and heavy excelaration. After startup and normal driving not too bad. Has 70k original on 351c 4V. Sat for about 10 years until body restore. Runs pretty strong other wise. Hoping just selas - Any bets - seals, guides, rings?

Click to expand...

Shade tree mechanic 101:
1. Smoke under acceleration...............rings
2. Smoke under decceleration.............valve guides
3. Engine knock under acceleration.....BOSS-302 broken piston noise
4. Engine knock under decceleation.....wrist pin
5. Engine knock all the time................big-end rod bearings

 

P

palerider94

Member

Feb 21, 2006

573

1

19

Sep 18, 2007

#6

• Sep 18, 2007

• #6

Notice more under deceleration.

Oh well worst case need to rebuild. There goes my flipping it and making a few grand.

 

StangDreamin'

Founding Member

Aug 10, 2002

583

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2nd Ocotillo bush east of the Colorado River; Sout

Sep 18, 2007

#7

• Sep 18, 2007

• #7

Seen any "lumps" in old oil as you drain it? Investgate the lumps to find they were very brittle "half-cylinder" shapes, that were never more than 1/2" long? Do your rocker cover gaskets leak - a lot?(Like the oil isn't draining out of the top of the heads very well?)
One last one, does she belch out a puff of smoke on startup?

You said smoke on decelleration; couple that with any one or two of the above questions; and I bet "stem seals +2".

Been there, done that. Not that hard a fix on the Cleve, as I remember.....

 

ratio411

Founding Member

Apr 21, 2002

3,870

73

109

Pensacola FL

Sep 18, 2007

#8

• Sep 18, 2007

• #8

I would say valve seals (umbrellas).
They can dry rot even when the car sits idle for a couple years.
After 10 years of sitting, they are probably toast!

Keep optimistic and swap those out first.

There is probably smoke from valve guide wear too, but it is only heavily magnified when the seals are bad. Might clear up 80% or better with umbrellas.

 

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danny clemens

Member

May 4, 2005

728

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Sep 18, 2007

#9

• Sep 18, 2007

• #9

Probably a combination of all of them but I'd just change the valve seals and go from there. That might fix it enough to make it driveable and wouldn't cost you an arm and a leg.

 

P

palerider94

Member

Feb 21, 2006

573

1

19

Sep 19, 2007

#10

• Sep 19, 2007

• #10

Stangdreamin
the Rocker covers (aka valve covers) do look like they are leaking - tightened down - both sides where like hand tight. Tightened but still look a little wet. Also around breather cap going into air cover - seems a little more moist than on my 302.

 

D

D.Hearne

New Member

Sep 29, 2000

11,730

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south louisiana

Sep 19, 2007

#11

• Sep 19, 2007

• #11

Valve seals, the stock umbrellas are notorious for rotting in place after sitting idle. Even running, they eventually "cook" and do the same thing. The 68 Merc I had unitll last year sat for long periods (it had 58K on it when I bought it back around 02-03) When I took the heads to the machineshop after it popped a head gasket and ran 300* all they needed after 34 years was new seals.