Compression test procedure?

sholxgt · August 12, 2016, 03:38:37 PM

I'm trying to wrap my little brain around what you said. If you have air coming up out of the cylinder, wouldn't that mean a leaking valve stem seal?

Edit - thinking more about it, I think that it could show rings or valve seals. Right?

SHOdded · August 12, 2016, 03:40:08 PM

Interesting the car runs smoothly other than at idle even with that severe a leakdown.

Spenser281 · August 13, 2016, 10:00:56 AM

sholxgt- you're correct. Air is getting past the compression ring, going into the crank case and, during the leak down test, with the oil filler cap removed, you can hear and feel the air coming out of the oil filler tube.

SHOdded- I've started noticing a slight vibration, the same you might feel with with a misfire, when the vehicle is under load at low RPM. For example, when driving up a hill on the highway. I can feel a slight vibration.

My theory is that with the car only having 81k miles on it, is that either the compression ring or ring land is broken. But I have a feeling the oil control rings are still intact and that is why I'm not getting any smoke......yet.

Still no misfires.

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Spenser281 · August 13, 2016, 10:04:43 AM

Oh....to add to this, I have called 3 different dealerships and evidently Ford has the 3.5 Ecoboost on backorder due to an update in tooling. Any one have any insight on this? I have no clue whether this effects both the transverse and longitudinal engines, or just the transverse. Either way.....I'm a little screwed right now.

Does anyone know if the 13+ transverse engines will work in the 10-12 applications?

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sholxgt · August 13, 2016, 11:08:41 AM

This is very interesting to me because my car has poor idle quality and I have a stutter that happens between 1400 and 1500 rpm. Mostly only when going up hill. The stutter does not show up in data logs though. So, mine is not a misfire. Just an irritating stutter. Been thinking that mine is converter related, but now I wonder...

Good luck to OP!

SHOdded · August 13, 2016, 11:10:54 AM

With a few parts/sensor changes, the 13+ engines can work with the 10-12s. Waiting for a "definitive" list from a SHOforum member.
http://shoforum.com/index.php?threads/2010-sho-threw-a-rod-new-motor-required.132357/page-3#post-1457410

That slight vibration while driving might be from the PTU. There is a TSB out for it, see if it fits what you are seeing:
http://www.revbase.com/BBBMotor/TSb/DownloadPdf?id=169301

The PTU is/should be disengaged in Park and Neutral.

Spenser281 · August 13, 2016, 11:56:49 PM

Thanks for the heads up on the TSB. It somewhat fits the description, but I just started noticing it about the same time as the rough idle, so I'm assuming it is attributed to the weak cylinder. I suppose if it continues doing the same after the engine is replaced, I will dig into the PTU next.

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sholxgt · August 27, 2016, 06:13:53 PM

Just finished doing a compression test on mine. All cylinders were between 172-178.

Looking more and more like my stutter is transmission related.

Thankfully, I will not be fighting Spenser trying to find a new short block

Spenser281 · August 27, 2016, 10:36:32 PM

Those numbers look perfect. Hopefully you get the shudder figured out.

As for fighting me for a short block, I'm terribly sorry to disappoint you, but I bought a used engine off of eBay and had it sent Livernois for some work.

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SHOdded · August 27, 2016, 10:56:25 PM

Looking forward to the results, Spenser!

sholxgt · August 27, 2016, 11:43:39 PM

Quote from: Spenser281 on August 27, 2016, 10:36:32 PM
Those numbers look perfect. Hopefully you get the shudder figured out.

As for fighting me for a short block, I'm terribly sorry to disappoint you, but I bought a used engine off of eBay and had it sent Livernois for some work.

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That's exciting! I love to see someone turn a problem into an opportunity. Can't wait to hear more as your adventure continues.

Gjkrisa · August 29, 2016, 01:08:12 PM

Quote from: Spenser281 on August 12, 2016, 03:30:19 PM
Performed a lead down test today. Cylinder #6 is leaking air out of the oil filler tube on the valve cover. Also getting about 60% leakage. I checked two other cylinders just to verify I was getting it right. Only showing about 3% leakage on them. So since the air is coming out of the oil filler tube, that leads me to conclude that it is a broken compression ring. Ugh.

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If it is bad rings just change the rings and maybe the piston $500 at most for parts not sure if it would be possible to do the work without pulling the engine as I am away from my car till the 8th to get a closer look at the possibility.

Also did you try the table spoon of oil to see if compression gets better?

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Spenser281 · August 29, 2016, 10:06:44 PM

Quote from: Gjkrisa on August 29, 2016, 01:08:12 PM
Quote from: Spenser281 on August 12, 2016, 03:30:19 PM
Performed a lead down test today. Cylinder #6 is leaking air out of the oil filler tube on the valve cover. Also getting about 60% leakage. I checked two other cylinders just to verify I was getting it right. Only showing about 3% leakage on them. So since the air is coming out of the oil filler tube, that leads me to conclude that it is a broken compression ring. Ugh.

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If it is bad rings just change the rings and maybe the piston $500 at most for parts not sure if it would be possible to do the work without pulling the engine as I am away from my car till the 8th to get a closer look at the possibility.

Also did you try the table spoon of oil to see if compression gets better?

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Too late for that. I've already bought a used engine off of eBay and sent it to Livernois. I'll most likely have them do rings and bearings. Obviously if the cylinder is scored too bad, I may be doing a set of pistons. My checking account will do the majority of the decision making.

As for whether re-ringing cylinder 6 with out pulling the engine, I suppose it's possible. But I don't think I'd want to attempt it.

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Gjkrisa · August 29, 2016, 10:19:15 PM

Have you talked to them about port polish and closed deck?

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Gjkrisa · August 29, 2016, 10:47:03 PM

I've read on the forum that port polish is not necessary but most likely the heads are a cast so there are going to be cast lines more air you can flow less restrictive the better and they have a flow bench to test how much more they can get it

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