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Tim Mohr
Category: Car
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Lincoln Aviator: low compression on drivers side cylinders..TSB

Customer Question

My Lincoln Aviator shows low compression on drivers side cylinders. There is existing TSB for this problem. What exactly is the problem causing low compression? I have 110,000 miles on my Aviator which is in excellent condition otherwise, and do not wish to trade it as they don't make them anymore. Since the engine has to be removed due to location of timing chains on rear, would cylinder head r/r fix this problem? My Aviator has had all recomended maintenance thru Dealer.
Submitted: 7 years ago.
Category: Car
Expert:  Tim Mohr replied 7 years ago.
Hi, my name is XXXXX XXXXX is usually caused by a bad timing chain, since these only have a camshaft sensor on bank 2, the only way to verify this is by disassembling the heads, but it is very common for the timing chain to stretch on these,Tim
Customer: replied 7 years ago.
I'm thinking that you don't really have any knowlege with this compression problem regarding Lincolns, both Navigators and Aviators. I have had both Ford dealer and Goodyear run diags and got their recommends, but no detailed explanation on the exact problem. Timing chains have to do with ignition timing, not anything to do with cyliner compression. So, I don't accept your answer.
Expert:  Tim Mohr replied 7 years ago.

i have extensive experiance with these motors, there are 4 timing chains on this motor, one for the left head, one for the right head, and one each for the dual cams, if one has stretched or broke, it will effect the compression on only one head,I will post a diagram showing these 4 chains,Tim

Expert:  Tim Mohr replied 7 years ago.
Customer: replied 7 years ago.
I already know what a timing chain looks like, and the engine diagram! The TSBs and the blogs mention only doing a valve job or replacing the heads, so I already know this. I wanted to know which part of the head the problem is located, and you don't have the answer. I will return to the dealer and ask the mechanic there. I have extensive experience with cars from about 1973 to present, including the performance rebuild of a 428 SJC Mustang. I am disabled and can no longer work on cars myself, but I know my way around. Was thinking it must be in the valve guides or the machining of the head itself. The TSB (technical service bulltetin) from Ford was listed as before I even bought the car, and rough running then would not have been from a new timing chain.