Rough idle- 1999 S80T6 2.8L

mlanctot · Post by **mlanctot** » 02 Jul 2008, 08:21

Shop just called back to say that cylinder #5 has low compression. I am a little surprised, maintenance has been faithfully performed on a regular basis.
My question to this board is how likely to have a piece of scale hang on a valve and cause low compression. Would some hard driving possibly clear this up. I do not hear often these engines going bad. Any comments?

Thanks

les & reilly · Post by **les & reilly** » 02 Jul 2008, 08:30

you could always try an additive in your tank which removed carbon deposits, never tried them myself as upto now i havent needed it, but it would save alot of expense of stripping the top end.

Post by **MadeInJapan** » 02 Jul 2008, 08:43

Read up on SeaFoam... many here claim it "fixed" just the issues you speak of in this thread.

mlanctot · Post by **mlanctot** » 04 Jul 2008, 04:21

Well I went to NAPA and spoke with the owner. He said it has worked in some cases. Bought two cans. One can was sucked through a vacumm line and the other in the gas tank as explained by Brian at NAPA. So far no change but I did manage to smoke up the yard.

In the event that indeed an intake valve is indeed burnt. Can the head be removed and sent to a shop for rebuild.? I've done a little homework here but information is sketchy. Alldata helps but I really need a shop manual.

Thanks

les & reilly · Post by **les & reilly** » 04 Jul 2008, 04:29

i dont know which country you are in, but in the uk there is a product called redex which you put in the fuel tank.
this is supposed to remove build up of carbon in the cyclinders.

les

mlanctot · Post by **mlanctot** » 05 Jul 2008, 17:56

Put Seafoam in the gas, in the crankcase and the vacuum line. I only ran the car for about twenty miles than changed the oil. I was told to be careful about spinning a bearing. So after all this the car has a changed idle, not perfect but more even. Shall monitor and see what happens.