Compression test results

Just looking for some input on the results I got from doing a compression test on my engine. Truck has 175k on it and I'm not burning any oil. Test was done with a home made harbor freight compression tester.

Cylinders
1- 360psi
2-360psi
3-375psi
4-360psi
5-375psi
6-360psi
7-360psi
8-360psi

All glow plugs were pulled and each cylinder was tested twice with 6-8 cranks per cylinder.

Not exactly ideal compression, but that aint bad either. Probably has another 100k in it easily.

Thanks for the input. That's also assuming my gauge sealed completely and gave me an accurate reading too.

harbor freight compression testers will not produce correct numbers. that's what I started with. I ended up buying a tester from Snap-On. I used the grease hose and fittings to hook up tester from hf. the grease hose had spots on where it was starting to bubble on the side of the hose. the harbor freight tester was off by at least 40psi.im sure if you had something better than hf brand your comp numbers would be better. some things from hf are good, not the compression tester.

I was questioning how accurate the harbor freight tester was. I just had a hard time justifying the cost of the snapon tester for me to only use it once.

Are you having cold start issues? I have compression checked A LOT of 7.3 engines and those numbers aren't bad at all.

Your altitude will affect numbers too.


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I have no cold start issues other then then normal cold start smoke. I'm in Illinois so not much altitude here.

Yes I had a hard time trying buying snap-on,but I'm sure I will us it again sometime.i did not buy the complete kit, I bought the comp. tester and the adapter for the 7.3 psd.the whole kit was maybe 560.00 most of the other pieces I don't think I would use.i can buy the other adapters if needed.i think I have about 360.00 in what I bought.

psdguy95 said:

I have no cold start issues other then then normal cold start smoke. I'm in Illinois so not much altitude here.

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Im in il too. Anything over 320 is decent....360+ is tight....400 is perfect...

Jcv1990 I didn't know you could get the tester separate. I'll have to ask my snapon guy about it.

Tycorr thanks for clearing that up. So it looks like my motor is healthy then

Gauge aside, they're all inside 5% of each other so it's all good.

EEPD500-diesel compression guage $237.00, EEPV314C-compression adapter for glowplug port on 7.3 powerstroke $56.75.you can buy the rest as needed, In snap- on book you can get the parts of the kit through the service repair kit.

mandkole said:

Gauge aside, they're all inside 5% of each other so it's all good.

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Thats what i figured since they were all close to each other. Just wanted a second opinion. Thanks!

jvc1990 said:

EEPD500-diesel compression guage $237.00, EEPV314C-compression adapter for glowplug port on 7.3 powerstroke $56.75.you can buy the rest as needed, In snap- on book you can get the parts of the kit through the service repair kit.

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Sounds good. Ill ask my snap on guy about it this week