Hi, I bought a 1997 F-150 about 3 months ago off a friend of mine. It has a rebuilt engine in it with less than 5000klm on it. When I bought the truck I was told to put 10w30 in instead of 5w30 (I'm guessing to cover up an underlying problem). I had the oil changed the other day and put 5w30 in instead of the suggested 10w30. About 5klm after I started hearing a knocking noise from the right side of the engine and have significantly reduced power. I am almost positive one of the cylinders is not firing. I drove it around town a bit to see if the problem would correct itself and the check engine light came on and than started flashing but I reset it in a feeble attempt to solve the problem (I was 75klm away from home and had to get back) So I cant hook up a diagnostic computer until it comes back on. If anyone has ANY ideas or suggestions they would be much appreciated. Thanks

 

Some friend.
There is an additive you can add to the oil that is supposed to help with knocking and such. I can't think of what it's called, but you can get it at any automotive store. It's a thick oil like liquid (might be called compression booster). This of coarse is only a bandaid for a larger issue.

 

thanks for the suggestion Bullitt94. I think I am going to pull the engine and rebuild it myself to make sure no corners are cut. As I mentioned before I had reset the computer. I am trying to make the check engine lite go back on so I can diagnose the problem. Does anyone know how long it will take for the light to go back on or if I can still pull the codes after unhooking the - battery.

 

Usually the light will come on right away when the computer sees the problem. You could try reading the codes. Maybe they were stored through the battery disconnect, but I doubt it.

 

I would still try to pull codes. Some codes are "HARD CODED" and will not reset by disconnecting the battery. The "HARD CODED" codes can only be cleared with a scanner, so something may still be there.

As far at the engine being "REBUILT"...Yep, know where you're coming from as my version or "REBUILDING" is far different than somebody elses. I always say..."If there are two pieces assembled together, they get un-assembled"

 

So I took it down to Mr Lube (they will scan the EBD for free and the only one I know with an EBD scanner is out of town) but it came up with nothing and of course they don't know how to do anything but a simple scan. So I got fed up and took it in for a diagnose and it turns out it was the coil pack. I didnt check for a spark because the guy at Mr Lube did for me, said it was good and I was stupid enough to bileve him (First and LAST time I get somone els to change my oil). I swaped out the coil pack and she runs the same as she used to. It turns out the knocking noise is a crankshaft bearing that was acting up because the piston wasnt firing, that explains the 10w30. I had a bit of a felling it was a crankshaft bearing but I was told they were replaced so I ruled that out. Now I'm thinking the "rebuild" was just a engine swap. So, I think when I get back from vacation I will pull the engine replace bearings, pistonrings, personly inspect and replace anything that has to go but I dont love her enough for a full rebuild. Thanks for all the advice its greatly appreciated.

 

When you got it apart for new rings, don't forget to run a hone thru the cylinders to "DEGLAZE" the cylinder walls so that you get a good seating of the new rings. This will also show any "OUT-OF-ROUND" spots in the cylinders.