My valves are rattling when I gas it

Tiny
MIKEP
  • MEMBER
  • 1995 CADILLAC DEVILLE
  • 100,550 MILES
I have a 1995 cadillac sedan deville with a 4.9 liter engine and 100550 miles. About 800 miles ago I had the plugs and oil changed. The valves rattled on acceleration so the mechanic used an oil additive called Seafoam. It quieted the valves for a couple
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Tuesday, November 1st, 2011 AT 1:05 AM

9 Replies

Tiny
MIKEP
  • MEMBER
Not sure where it cut off but the oil and plugs were changed at 998500 and the valves rattled so the mechanic put Seafoam in the oil to quiet them and it worked for a couple days then I noticed a flutter in what sounded like the bottom end, sort of like the old heat exchangers used to make, like a faint knock. The mechanic couldnt diagnose and said wait till it gets louder. Meanwhile the trans breaks and needs rebuilding. Aamco assured me thats what the knock was but $2400 later and its still there and a little louder. My mechanic says take it to Cadillac but that will cost me an arm and a leg and still may not know without a tear down of the motor. The noise is only there on acceeleration
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Tuesday, November 1st, 2011 AT 1:39 AM
Tiny
MIKEP
  • MEMBER
I'd like to add that it doesn't start to knock until it's warmed up, about 2 miles into it.
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Tuesday, November 1st, 2011 AT 11:35 AM
Tiny
CADIEMAN
  • MEMBER
Put lucas engineoil tretment in and new oil. Your gonna need a used engine and rebuilt trans. Is this car worth fixing.
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Tuesday, November 1st, 2011 AT 3:29 PM
Tiny
FIXITMR
  • MEMBER
Might wanna get the oil pressure checked. What oil was put in? Not 5-30?
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Tuesday, November 1st, 2011 AT 8:50 PM
Tiny
MIKEP
  • MEMBER
I think they put 10-30. 5-30 is the recommended oil I believe. I was going to use the "High Mileage" oil in the recommended weight and the lucas oil treatment. Does that sound right or should I be using a different oil? I've always used Castrol in my cars but I've gotten older and lazier and now pay someone to do it. Appaerntly a bad move on my part. Do you think the Seafoam had something to do with it? Ran quiet and smooth before the service. It even runs a little rough now like there's a miss or a plug not firing but the onboard monitoring system says "All monitored systems ok".
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Tuesday, November 1st, 2011 AT 9:23 PM
Tiny
CADIEMAN
  • MEMBER
If its ran smooth before the previous repaires. Have the motor scoped to find a bad plug or wire.
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Tuesday, November 1st, 2011 AT 9:42 PM
Tiny
FIXITMR
  • MEMBER
Yah I let someone else do some work on 1 of my cars and they messed it up a little too. What oil was in it before change?
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Wednesday, November 2nd, 2011 AT 3:06 AM
Tiny
MIKEP
  • MEMBER
5-30
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Wednesday, November 2nd, 2011 AT 10:37 AM
Tiny
CADIEMAN
  • MEMBER
When engines get hot the engine bearings get to much clearance and knock. Check the oil pressure and go from there. Your having two problems. Valve tap in a caddy is caused by timing. Did these idiots set your timing?Youll need to retard the timing by 2 degrees will quiet those valves down. Find a different shop also
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Wednesday, November 2nd, 2011 AT 3:00 PM

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