Big Trouble

daf290

Registered
My 95 with 150k miles developed a miss, I drove it home about 30 miles and started researching the problem. I changed plugs and found two front plugs on the pass side slightly wet. After changing the plugs, I started it and still had the miss, while I was checking for vacuum leaks, it made a really bad upper valve train noise. I immediately shut it down and highly suspect a broken valve spring. I think it is on the pass side but I don't know any way to tell except remove the valve cover. I will pull the pass valve cover tomorrow and see what I find.
 
RE: Big Trouble

What type of oil have you been runnning? Try to take off the oil cap with the engine running, try to look in there and see what's going on, you might be able to spot something. Taking off the valve covers is not easy. I would also run a code scanner for codes and do the cylynder balance test. Good luck.
 
RE: Big Trouble

older 4.6 DOHC's are known for developing these kinds of problems at higher milages.
 
RE: Big Trouble

Well the motor is trash!!
I pulled the pass side valve cover, I knew I was in trouble when I pulled the #1 plug and the electrode was smashed closed. The lower rear valve rocker came off in my hand. The valve spring was broken but the rear problem is that the valve stem is broken right at the tip and the valve is somewhere in the cylinder.

Darn!

I have a slightly crashed 96 in the garage with 66k miles that I was rebuilding to replace the 95, I guess it just got fast tracked!
 
RE: Big Trouble

Wow that sucks. The good thing is that you can a find Mark VIII engines at junkyards everywhere for cheap if you ever wanted to go that route. I'm still curious as to what oil you have been running in that engine?
 
RE: Big Trouble

Mobile 1 10W-30 Since it had 50k miles on it. I don't believe the valve springs would be oil related. The bottom end is still solid.

Anyone want a really nice 95 Mark with no motor in Pittsburgh??

New trans at about 110k miles. All new front end, everything from struts (non air) to rack.

I will really miss that car!
 
RE: Big Trouble

10w-30 is too thick of an oil for the 4.6 DOHC. You need to use 5w-30 Mobil 1 on these engines. Maybe even the new 0w-30 Mobil 1 for better cold starts. But 10w-30 is definately too thick for these engines.
 
RE: Big Trouble

[div class="dcquote"][strong]Quote[/strong]
10w-30 is too thick of an oil for the 4.6 DOHC. You need to use 5w-30 Mobil 1 on these engines. Maybe even the new 0w-30 Mobil 1 for better cold starts. But 10w-30 is definately too thick for these engines.
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Unless you live in LA, where the temp NEVER gets below 40.
 
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