Low compression?

JOSHUA LOUIS CORNETT

MEMBER
2005 FORD FIVE HUNDRED
3.0L
V6
2WD
AUTOMATIC
200,000 MILES

I have 3 cylinders on the same bank with low compression, the car starts but does not have enough power to move its own weight.

Wednesday, July 19th, 2023 AT 7:50 AM

5 Replies

KEN L

MASTER CERTIFIED MECHANIC
47,643 POSTS

It sounds like you broke one of the timing chains, this is not good because it can bend the valves. You can confirm the issue by removing the valve cover on the side with low compression and confirm the camshaft is not turning while the engine is being cranked over. Please go over this guide as well:

https://www.2carpros.com/articles/the-reasons-for-low-compression

Check out the images (below). Let us know what happens and please upload pictures or videos of the problem so we can see what's going on.

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Thursday, July 20th, 2023 AT 11:30 AM

JOSHUA LOUIS CORNETT

MEMBER
3 POSTS
2005 FORD FIVE HUNDRED
3.0L
V6
2WD
AUTOMATIC
200,000 MILES

So the car starts up when its at idle cannot tell there is any problem everything is normal as soon as you press on the gas it falls flat it can't move itself under its own weight took it to shop they said it has low compression in 3 cylinders on the same bank its not the timing I took valve cover off and checked that

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Saturday, July 22nd, 2023 AT 4:00 PM (Merged)

KEN L

MASTER CERTIFIED MECHANIC
47,643 POSTS

If you have three cylinders on the same bank with low compression you probably have a clogged catalytic converter on that side.

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Saturday, July 22nd, 2023 AT 4:00 PM

JOSHUA LOUIS CORNETT

MEMBER
3 POSTS

Wouldn't be a clogged catalytic converter.

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Saturday, July 22nd, 2023 AT 8:29 PM

KEN L

MASTER CERTIFIED MECHANIC
47,643 POSTS

Good point, can you remove the primary oxygen sensor and then recheck the compression that should tell us for sure if the catalytic converter is plugged. Check out the images (below). Please let us know what happens.

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