4.6L 2V compression test results high?

[Falcon_LS]

Back when I was replacing the plastic intake manifold on my 4.6L 2V, I borrowed equipment from a friend to do an engine compression test after the new intake was installed. The results seemed too high, and as this was the first time I did this, I didn't think much of it. This was in October '11 with 266,922 km (166,826 miles) on the clock:

#1: 196
#2: 200
#3: 198
#4: 200
#5: 200
#6: 200
#7: 200
#8: 196

Just wondering if these are acceptable to someone with experience, or if they really are high. This was just brought up during a conversation with someone today, who said 150 is the average, and there probably was a problem with the gauge. For the record, I did this when the engine was hot with all the plugs out and the ignition coils removed. Thanks!

 

[Boomer]

Whatever the real values, the consistencty from cylinder to cylinder is excellent unless the gauge is pegging.

 

[The_Eric]

It's unlikely that the compression is too high. Over the years cranking compression has been climbing, so I'm not surprised to see it there. In fact many 4 cylinder engines I've done have been in that range. Like Boomer said, consistency cylinder to cylinder is what is important and you've definitely got that.

If you're still concerned, get a factory manual and look it up, but also remember that gauges will vary. For example, my gauge seems to read higher than most.

 

[demarpaint]

If you feel the need to check again use a different gauge. The numbers seem a bit high, nothing to worry about though. The consistency from cylinder to cylinder is excellent, and really what matters here. They're within about 2% of each other which is very good, and why I would probably check again with another gauge. LOL

 

[ARCOgraphite]

better all consistent than a couple reading 90

Testing warm is good.

 

[TFB1]

Unless that compression tester was designed by the Ford engineers that also designed their numb oil pressure gauges, as far as variance those are outstanding readings, generally a 15-20% variance is acceptable...

I'd think readings are approx 20-30psi high, but that's far better than being low... A high reading is generally because of carbon build up in the cylinders, as long as you don't have a spark knock/detonation problem, life is good...

 

[Dakota1820]

My Saturn's compression was 196 194 195 196 its got 193,000 when I tested it. I think your numbers are good. Could be q little carbon just run a can of seafoam. But I think you have nothing to worry about.

 

[mechtech2]

This can be very normal, nowadays.
Even turbo engines, which historically had low compression, are very high now. Tuning and variable cam timing account for this.

 

[Falcon_LS]

Thanks for all the input. According to the Ford Service Manual, apparently it is possible to have compression readings of 200 and higher. I suppose there won't be any harm done to check again with another gauge.

 

[mechtech2]

I wouldn't waste my time with a recheck. The readings are consistent, which is a huge plus.
Enjoy your tight engine!

 

[Falcon_LS]

Thanks, Mechtech2!