[sm=americanasmiley.gif]Help, I just boughta 1984 Biarritz convertible (My first Caddy)and the valves start tapping (almost knocking) when the engine gets fully warmed up (it runs pretty good when cold). Also the car seems to lose power.I can only hear this from the drivers side top.The car hadbeen sitting for a few years. I put a can of Marvel Mystery oil in with the last oil change. Anyone have any Ideas. Thanks, John

 

Hey there 84: Nice flags there dude. You could try running a heavy oil in your engine. In the summer I run a 20/50 in my 368 and it seems to do the trick. Shy of that I think you would need a lifter kit.

 

You may have the same problem I had with my 4.1L that had sat a while. Try your mystery but if it doesn't work...
This is a lot easier and cheaper than a Lifter fix so I hope this is the problem. The lifters get gunked up and put extra pressure on the rocker arms which put extra pressure on the roller rockers, which cause the Rocker arm support to break at the roller rocker screws. This causes the roller rockers(Part that holds rockers together in pairs) to break in half. This allows the rocker arm to turn slightly sideways and the pushrod will actually come up and hit the underside of the valve cover. when this happens, the car will still run but will be noisy (Click clack) and power will certainly suffer.
How to tell:
Remove valve cover and look. See if any rockers are extremely loose or have turned sideways like I said. IF so, order a replacement rocker support arm from the cadillac dealer No.352-1181(Two if the problem is on both sides(listen withscrewdriver on head near ear and end on valve cover)(Or buy cheap stethescope for this purpose from parts store) You will also need to replace the broken Roller rockers(part that holds the rocker arms together in pairs(they break easily)Use 8mmx125mm Tap to create threads for rocker roller screws into your new support bar(GM says screws are self-tapping-mechanics say don't do it that way) Screw your rocker rollers -all of them -to the rocker arm support before screwing to head as an assembly-important. Screw assembly onto head. On some older engines you will not have screws or bolts for arms that(Hang down on support bar-just ignore this and fasten it in using 6 nuts? in center of bar already used from old one. There is only one replacement part available for this and it fits all 4.1L engines.(Mine didn't have the bolts for the decending arms and it works fine. With a new rocker arm support and some mystery oil in the crankcase, your lifters will clean themselves and function without issue but you must drive it occasionally.

 

Rocker rollers are also called pivots. they say to torque pivots to rocker arm support 30NM or 20 ft lbs(MY buddy says these are not exactly equal.) be carefull and make sure you know how your torque wrench indicates. The new ones just release for a little bit and you have to be carefull to notice the torque indication. Use your head-if you think you're going to break it-back off and ignore the torque. They say use 50NM or 35ft lbs for the head bolts that fasten the rocker arm support.

 

FYI rocker arm support is about $35 and the Roller rockers/Pivots are $15-20.

 

More history-I bought mine(1984 Seville, also have 84 eldo) from a dealer who was able to prove they got it from the original owner who was, in fact someones grandmother. Car had sat for 6-8 years and looked like it. The engine had power but sounded like lifters. The dealership mechanic said to put in risolone or mystery oil and it would quiet right down. Instead IT got noisier and then refused to start. Took me a while to figure all this out- I had two pairs of lifters not functioning when I took the valve cover off and looked.(thats two intake and two exhaust valves not opening) The pushrods were actually tapping the underside of the valve cover-that was the noise I heard. This is common on 4.1L cadillac V-8's. Actually it happens on latter model engines with the support bar arrangement just not as much. They use the bar because the aluminum head is not strong enough to hold the torque produced by the lifter/rocker combination. They sell a lot of support bars at the dealership.
Check this out yourself if the noise won't go away. Don't pay anyone to do this it's really easy and has a big "Pride factor" when you finish and the engine starts right up and purrs.


Good luck and post any questions and I'll see if I know.

 

[sm=americanasmiley.gif]Thanks pkared,I had already pulled the valve cover and found what looked like one loose rocker arm set. I removed them and swapped the intake and exaust. ( Is this good or bad). So far I have only driven about 35 miles and the tapping has not returned. I will probably not drive it for a couple of days as I am replacing the idler arm and both passenger side tie rods. (Any one know the the bolt size for the Ilder arm bolts.) Any help on this motor will be greatly apreciated. Thanks, John Masson Westford, Ma[sm=americanasmiley.gif]MADE IN THE USA

 

If it works I guess run with it but I wonder how long it will stay quite. Swapping is a strange fix but if it works... Did you make sure the rocker arm support was not broken in any place(It can be hidden by the Large nuts that hold it on-They often break at that point) If you were able to swap arms it sounds like the pivot hole (Or Holes)were not stripped. If problem returns and they are stripped, Go for the hole assembly rebuild I layed out and all will be well.
BTW I have the '84 Seville and Eldo Same color and the Eldo is more fun to Drive without question, I sure wish it was a convertible. They're well worth the effort you put into 'em. Try the other forum topics for the Idler arm question if nobody answers, I havn't had any suspension issues excepy replacing spring & shocks. Always watch ebay before buying anything, they have a lot of Eldo parts there. How are your Lift shocks for the hood and trunk? they're available on ebay now for cheap, new.