Attn: PKRWUD: Compression Test Results

95mustanggt · 07-06-2002, 03:49 PM

Ok I got myself a compression test kit. It was only $42 (Canadian

). I eyed up a coolant test kit and it was $54, I didn't buy it because my wife might kill me.

Both #4 and #8 are a B!tch to get the fitting in, but I did get them in eventually (after a few...many...choice words).

Cylinder# Pressure

1 152
2 150
3 145
4 145
5 140
6 145
7 146
8 149

I got the car warmed up and stared to take things off. I removed the front brace and cold air ducting. I then removed all 8 wires then all 8 plugs. I checked the gap on most of them. It was between 0.050 and 0.055.

I started at #1 and went to #8 (well I actually skipped #4 and came abck for it after #8)

The car had cooled down some (it took some time to get #4 and #8) but even at the end the adapter was almost too hot to hold.

I cranked it over 5 times on each cylinder.

I started thinking about the gas smell, could I just have a screwed injector? Or maybe a crack in the intake manifold?

Well I hope this is enough to generate some ideas.

PKRWUD · 07-06-2002, 05:07 PM

Okay, good news/bad news.

The good news is that you don't have a blown head gasket. In fact, your test results were very respectable. Your engine has even wear, and is doing nicely.

The bad news is that you need more test equipment. Specifically, you need a fuel pressure tester, a cooling system pressure tester, and a vacuum gauge. The fuel pressure tester is comparably priced to the compression tester, and the vacuum gauge should be no more than $15. You should have your cooling system pressure tested, too, but those kits are usually $75 or more. Down here, there are auto parts stores (Kragen, for one), that will loan you tools for a small, refundable deposit. I would recommend borrowing a cooling system tester, and purchasing a fuel pressure tester and a vacuum gauge.

The fuel pressure tester will tell you if you have a leaking injector, and the cooling system pressure tester will tell you if you have a leak in the cooling system, and possibly where it is. The vacuum gauge will tell you MANY things, and is, in my opinion, the single best diagnostic tool you can ever have.

Let me know what you decide, and what you would like to do, and I will walk you through it.

Take care,
-Chris

95mustanggt · 07-06-2002, 05:17 PM

Thanks Chris.

I think a fuel pressure tester is a good investment (even later when I have an AFPR).

The vacuum gauge I'm sure is also a good tool. I'll look at it too.

As for the cooling system pressure testing, I'll check my auto parts stores. I'm not too familiar with the stores here yet. NOTE: Anyone in Toronto know some good ones let me know.

Mopar1 · 07-06-2002, 05:29 PM

get both the fuel and vac gage. i use the vac gage all the time

95mustanggt · 07-06-2002, 07:59 PM

OK. I tried to get the tools tonight but the store was closed. I'll get them tomorrow morning.

I'm sure I can find a procedure to check the fuel pressure, but is there anything that I should be looking for? Is there anything special that I should do?

I'll probably get the vacuum gauge too. What am I looking for with it? Or should we take this one test at a time

.

PKRWUD · 07-06-2002, 08:39 PM

To check for a leaking injector, hook up the fuel pressure gauge, and turn the key on. After two seconds, turn it off, and then back on for another two seconds. Keep doing this until the gauge no longer goes up. Shut off the key, and watch the gauge. It should not drop at all for a minute. Does it? What about after 5 minutes? 10 minutes? let me know.

As far as tests with a vacuum gauge, where do I begin...

The vacuum that is created in a normaly aspirated engine (one that is not blown or turboed) gives you a great tool for diagnosing engine problems. Just about any internal engine problem can be identified with a vacuum gauge !!! I'll teach you some of the basics:

1) A steady reading of between 17" and 22" is considered normal for a stock engine.
2) A low but steady reading between 10" and 15" would be caused by retarded ignition or valve timing, or low compression.
3) A very low reading between 4" and 9" means you have a vacuum leak.
4) If the needle fluctuates as you increase the engine speed, you have either an ignition miss, a blown head gasket, a leaking valve or a weak valve spring.
5) A gradual drop in reading at idle means you have excessive back pressure or partial blockage in the exhaust system.
6) An intermittent fluctuation at idle means you have either an ignition miss or a sticking valve.
7) A reading where the gauge needle drifts anywhere between 12" and 22" indicates that your idle mixture is unstable. This is more common on carbureted motors.
8) A high and steady reading indicates that the ignition timing is too far advanced.
9) If, when you quickly close the throttle after running at 2000 rpm for ten seconds or more, the gauge needle DOES NOT jump two or more inches above what it is at idle, your piston rings are shot.
10) If the reading at idle is lower than normal, but the gauge needle fluctuates three inches on both sides of normal, your valve guides are excessively worn.
These are but only a few of the things you can learn about the condition of your engine with a vacuum gauge. Keep in mind that a blower or a turbo will create a false reading because the boost they create offsets the vacuum reading.

The following is the way to find out if you have an internal vacuum leak from a defective intake gasket:

1) Hook up a vacuum gauge to the intake manifold.
2) Fully close the throttle plate by backing out the idle screw all the way.
3) Plug up the PCV valve opening.
4) Disconnect and plug any vacuum hoses attached directly to the intake manifold.
5) Disconnect the wire to the positive side of the coil.
6) Crank the engine and observe the vacuum gauge. From 3" to 7" of vacuum (at a minimum of 250 cranking rpm) is normal. A defective intake manifold gasket will give, in most cases, a zero reading.

With a vacuum gauge, there are two easy tests you can run to determine if your exhaust is restricted (cats clogged).

First test:
1) Attach vacuum gauge to manifold vacuum source.
2) Observe vacuum at idle.
3) Snap throttle to WOT and release, while watching the gauge.

The vacuum gauge should drop to almost zero when you hit WOT. When the throttle snaps closed immediately after, the vacuum should read 4" to 6" higher than what it did at idle. It should then settle back at the same reading it was at idle before the WOT snap. This whole exchange should go from idle reading to idle reading in 2-3 seconds, tops. If it takes longer for the gauge to return to the same idle reading, your exhaust is restricted. The longer it takes, the worse the restriction.

Second test:
1) Attach vacuum gauge to manifold vacuum source.
2) Warm up engine.
3) Observe vacuum at idle.
4) Leave engine idling for 10 minutes. Do not touch anything on the car during this time. In fact, go inside and fix some coffee.
5) After 10 minutes, observe the vacuum.

If the vacuum is the same or higher, you don't have any resctrictions. If the vacuum gauge has dropped, you do have a restriction. The more it drops, the greater the restriction. If it drops 1" or more, you have a serious restriction. 2" or more and you might as well have the exhaust welded shut. Keep in mind that a rich exhaust will clog up cats in a hurry.

Hope this helps a little.

Take care,
-Chris

Bad89stang · 07-07-2002, 02:22 AM

Chris, what is the best book to learn some of this testing stuff? I am planning on taking some classes at a local junior college so that I can do some re-building and more detailed engine work. How about the rebuilding the small block ford book? Any help would be good. That way I don't have to keep copying and pasting all of your posts onto my "Mustang Tech" folder in my computer. That's a compliment by the way.

PKRWUD · 07-07-2002, 03:50 AM

Quote:

Originally posted by Bad89stang
Any help would be good. That way I don't have to keep copying and pasting all of your posts onto my "Mustang Tech" folder in my computer. That's a compliment by the way.

Well Thank You!!!

I am yet to find a book that has all this info in it. I have often thought about putting together a booklet of my favorite tips, but that would require writing one, and I'm not much on that. The best overall book that I could recommend is called Automotive Engine Rebuilding by James G. Hughes. I don't know if you'll be able to find it, though. My copy was printed in 1984, and was the required textbook for the Engine Rebuilding class I took at the local CC in 1986. It is filled with very good stuff to know, and if you can find a copy, BUY IT!! Then read it. Several times.

Take care,
-Chris

Bad89stang · 07-07-2002, 12:21 PM

O.K. thanks.... I'll see if I can find it on Ebay or something. I think the class would be my best investment. Thanks again Chris.

PKRWUD · 07-07-2002, 04:50 PM

No Problem! Good Luck!!!

Take care,
-Chris

skiwesser · 06-19-2004, 02:44 AM

Hey PKRWUD, I also get about 90% of my info from you.
Anyway you told me how to do vac. test on intake gaskets, but where do you hook guage for tests 1-10 in this post?
Thanks
Wes

stang_racer20 · 06-19-2004, 07:29 AM

Quote:

Originally posted by skiwesser
Hey PKRWUD, I also get about 90% of my info from you.
Anyway you told me how to do vac. test on intake gaskets, but where do you hook guage for tests 1-10 in this post?
Thanks
Wes

The manifild is the best spot. but anywhere after the the throttle body on a vacuum nipple.

skiwesser · 06-19-2004, 10:19 PM

Ok, I get it now.
Thanks PKRWUD, stang_racer20.

tmoss · 06-22-2004, 07:34 AM

Quote:

Originally posted by PKRWUD
The vacuum gauge will tell you MANY things, and is, in my opinion, the single best diagnostic tool you can ever have. Chris

That's "old school" experience talkin there - I'm come from that school. Here is a graphic that might help reinforce Chris' "lesson"..........

07-06-2002, 05:07 PM	#2
PKRWUD Junior Member Join Date: Mar 1999 Location: Ventura, California Posts: 8,981	Okay, good news/bad news. The good news is that you don't have a blown head gasket. In fact, your test results were very respectable. Your engine has even wear, and is doing nicely. The bad news is that you need more test equipment. Specifically, you need a fuel pressure tester, a cooling system pressure tester, and a vacuum gauge. The fuel pressure tester is comparably priced to the compression tester, and the vacuum gauge should be no more than $15. You should have your cooling system pressure tested, too, but those kits are usually $75 or more. Down here, there are auto parts stores (Kragen, for one), that will loan you tools for a small, refundable deposit. I would recommend borrowing a cooling system tester, and purchasing a fuel pressure tester and a vacuum gauge. The fuel pressure tester will tell you if you have a leaking injector, and the cooling system pressure tester will tell you if you have a leak in the cooling system, and possibly where it is. The vacuum gauge will tell you MANY things, and is, in my opinion, the single best diagnostic tool you can ever have. Let me know what you decide, and what you would like to do, and I will walk you through it. Take care, -Chris __________________ Webmaster: Rice Haters Club Jim Porter Racing Peckerwoods Pit Stop Support Your Local RED & WHITE!

07-06-2002, 05:17 PM	#3
95mustanggt Registered Member Join Date: May 2000 Location: Kamloops, BC Posts: 2,875	Thanks Chris. I think a fuel pressure tester is a good investment (even later when I have an AFPR). The vacuum gauge I'm sure is also a good tool. I'll look at it too. As for the cooling system pressure testing, I'll check my auto parts stores. I'm not too familiar with the stores here yet. NOTE: Anyone in Toronto know some good ones let me know. __________________ 1995 Mustang GT 20016 F150 Lariat Super Crew

07-06-2002, 07:59 PM	#5
95mustanggt Registered Member Join Date: May 2000 Location: Kamloops, BC Posts: 2,875	OK. I tried to get the tools tonight but the store was closed. I'll get them tomorrow morning. I'm sure I can find a procedure to check the fuel pressure, but is there anything that I should be looking for? Is there anything special that I should do? I'll probably get the vacuum gauge too. What am I looking for with it? Or should we take this one test at a time . __________________ 1995 Mustang GT 20016 F150 Lariat Super Crew

07-06-2002, 08:39 PM	#6
PKRWUD Junior Member Join Date: Mar 1999 Location: Ventura, California Posts: 8,981	To check for a leaking injector, hook up the fuel pressure gauge, and turn the key on. After two seconds, turn it off, and then back on for another two seconds. Keep doing this until the gauge no longer goes up. Shut off the key, and watch the gauge. It should not drop at all for a minute. Does it? What about after 5 minutes? 10 minutes? let me know. As far as tests with a vacuum gauge, where do I begin... The vacuum that is created in a normaly aspirated engine (one that is not blown or turboed) gives you a great tool for diagnosing engine problems. Just about any internal engine problem can be identified with a vacuum gauge !!! I'll teach you some of the basics: 1) A steady reading of between 17" and 22" is considered normal for a stock engine. 2) A low but steady reading between 10" and 15" would be caused by retarded ignition or valve timing, or low compression. 3) A very low reading between 4" and 9" means you have a vacuum leak. 4) If the needle fluctuates as you increase the engine speed, you have either an ignition miss, a blown head gasket, a leaking valve or a weak valve spring. 5) A gradual drop in reading at idle means you have excessive back pressure or partial blockage in the exhaust system. 6) An intermittent fluctuation at idle means you have either an ignition miss or a sticking valve. 7) A reading where the gauge needle drifts anywhere between 12" and 22" indicates that your idle mixture is unstable. This is more common on carbureted motors. 8) A high and steady reading indicates that the ignition timing is too far advanced. 9) If, when you quickly close the throttle after running at 2000 rpm for ten seconds or more, the gauge needle DOES NOT jump two or more inches above what it is at idle, your piston rings are shot. 10) If the reading at idle is lower than normal, but the gauge needle fluctuates three inches on both sides of normal, your valve guides are excessively worn. These are but only a few of the things you can learn about the condition of your engine with a vacuum gauge. Keep in mind that a blower or a turbo will create a false reading because the boost they create offsets the vacuum reading. The following is the way to find out if you have an internal vacuum leak from a defective intake gasket: 1) Hook up a vacuum gauge to the intake manifold. 2) Fully close the throttle plate by backing out the idle screw all the way. 3) Plug up the PCV valve opening. 4) Disconnect and plug any vacuum hoses attached directly to the intake manifold. 5) Disconnect the wire to the positive side of the coil. 6) Crank the engine and observe the vacuum gauge. From 3" to 7" of vacuum (at a minimum of 250 cranking rpm) is normal. A defective intake manifold gasket will give, in most cases, a zero reading. With a vacuum gauge, there are two easy tests you can run to determine if your exhaust is restricted (cats clogged). First test: 1) Attach vacuum gauge to manifold vacuum source. 2) Observe vacuum at idle. 3) Snap throttle to WOT and release, while watching the gauge. The vacuum gauge should drop to almost zero when you hit WOT. When the throttle snaps closed immediately after, the vacuum should read 4" to 6" higher than what it did at idle. It should then settle back at the same reading it was at idle before the WOT snap. This whole exchange should go from idle reading to idle reading in 2-3 seconds, tops. If it takes longer for the gauge to return to the same idle reading, your exhaust is restricted. The longer it takes, the worse the restriction. Second test: 1) Attach vacuum gauge to manifold vacuum source. 2) Warm up engine. 3) Observe vacuum at idle. 4) Leave engine idling for 10 minutes. Do not touch anything on the car during this time. In fact, go inside and fix some coffee. 5) After 10 minutes, observe the vacuum. If the vacuum is the same or higher, you don't have any resctrictions. If the vacuum gauge has dropped, you do have a restriction. The more it drops, the greater the restriction. If it drops 1" or more, you have a serious restriction. 2" or more and you might as well have the exhaust welded shut. Keep in mind that a rich exhaust will clog up cats in a hurry. Hope this helps a little. Take care, -Chris __________________ Webmaster: Rice Haters Club Jim Porter Racing Peckerwoods Pit Stop Support Your Local RED & WHITE!

07-07-2002, 02:22 AM	#7
Bad89stang Registered Member Join Date: Aug 2001 Location: Ft. Worth, TX Posts: 456	Chris, what is the best book to learn some of this testing stuff? I am planning on taking some classes at a local junior college so that I can do some re-building and more detailed engine work. How about the rebuilding the small block ford book? Any help would be good. That way I don't have to keep copying and pasting all of your posts onto my "Mustang Tech" folder in my computer. That's a compliment by the way. __________________ You're gonna need your seatbelt

07-06-2002, 03:49 PM	#1
95mustanggt Registered Member Join Date: May 2000 Location: Kamloops, BC Posts: 2,875	Attn: PKRWUD: Compression Test Results Ok I got myself a compression test kit. It was only $42 (Canadian ). I eyed up a coolant test kit and it was $54, I didn't buy it because my wife might kill me. Both #4 and #8 are a B!tch to get the fitting in, but I did get them in eventually (after a few...many...choice words). Cylinder# Pressure 1 152 2 150 3 145 4 145 5 140 6 145 7 146 8 149 I got the car warmed up and stared to take things off. I removed the front brace and cold air ducting. I then removed all 8 wires then all 8 plugs. I checked the gap on most of them. It was between 0.050 and 0.055. I started at #1 and went to #8 (well I actually skipped #4 and came abck for it after #8) The car had cooled down some (it took some time to get #4 and #8) but even at the end the adapter was almost too hot to hold. I cranked it over 5 times on each cylinder. I started thinking about the gas smell, could I just have a screwed injector? Or maybe a crack in the intake manifold? Well I hope this is enough to generate some ideas. __________________ 1995 Mustang GT 20016 F150 Lariat Super Crew

07-06-2002, 05:29 PM	#4
Mopar1 Registered Member Join Date: Mar 2002 Location: Lakewood, Wa Posts: 161	get both the fuel and vac gage. i use the vac gage all the time __________________ '77 Aspen R/T: 318 w/273 heads, 4spd, Hurst Shifter, 600 holley, edelbrock intake, 8 3/4 axle, 3.23 sure-grip, dual 3" exhaust, MP cam 276 / 276 duration 490 / 490 mech solid lifter, Super Stock Springs (15.65@88 3900lbs) '91 Mustang LX: .030 Bored, Typhoon Intake, 4.10's, Lentech VB, BBK 70mm TB, FMS A/C elim bracket, 19lbs inject, off road H-pipe, 75mm pro-m MAF, FRP unequal shorty, stormin normin hood. 3420 Lbs w/ 220 (me) and 13 gal gas. '02 SS Camaro

07-07-2002, 12:21 PM	#9
Bad89stang Registered Member Join Date: Aug 2001 Location: Ft. Worth, TX Posts: 456	O.K. thanks.... I'll see if I can find it on Ebay or something. I think the class would be my best investment. Thanks again Chris. __________________ You're gonna need your seatbelt

07-07-2002, 04:50 PM	#10
PKRWUD Junior Member Join Date: Mar 1999 Location: Ventura, California Posts: 8,981	No Problem! Good Luck!!! Take care, -Chris __________________ Webmaster: Rice Haters Club Jim Porter Racing Peckerwoods Pit Stop Support Your Local RED & WHITE!

06-19-2004, 02:44 AM	#11
skiwesser Registered Member Join Date: Sep 2000 Location: rock hill,S.C. 29730 Posts: 420	Hey PKRWUD, I also get about 90% of my info from you. Anyway you told me how to do vac. test on intake gaskets, but where do you hook guage for tests 1-10 in this post? Thanks Wes __________________ 88 GT: subs,pullies, 1 3/4 longtubes, flowmasters, AFR 165's,T,F #1 cam,Thyphoon intake, 24# inj., 73mm C&L,65mmT.B., 190LPH pump, Eagle sir rods, forged pistons in a newly rebuilt 306. DYNO TUNED TO 300.97 RWHP 337RWTQ

06-19-2004, 10:19 PM	#13
skiwesser Registered Member Join Date: Sep 2000 Location: rock hill,S.C. 29730 Posts: 420	Ok, I get it now. Thanks PKRWUD, stang_racer20. __________________ 88 GT: subs,pullies, 1 3/4 longtubes, flowmasters, AFR 165's,T,F #1 cam,Thyphoon intake, 24# inj., 73mm C&L,65mmT.B., 190LPH pump, Eagle sir rods, forged pistons in a newly rebuilt 306. DYNO TUNED TO 300.97 RWHP 337RWTQ

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