TECH 101 Compression testing 6.9/7.3 Engine

[riotwarrior]

Hello everyone, today we will be doing a compression test of a 7.3 IHI/Ford diesel engine in my 91 F350 4x4 RC truck. AKA White Rhino!

NO HATERS please remote starter switch, comp test kit (TU-15-53) as seen here http://www.toolsource.com/diesel-compression-test-p-95945.html and some 1/4" drive sockets and extensions etc for removing GP's and installing comp tester adapters, also note pad for recording the test data!

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Now prepping for comp test, start by removal of air cleaner and GP's wires

Here I"m indicating a GP with bullet connector removed

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Fuel stop solenoid wire that MUST be disconnected

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FOR SAFETY SAKE AND SO I AM COMFORTABLE, I elected to disconnect the FSS others may not this however is my choice and this is my thread!
Hard to see but now FSS is disconnected

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On my starter solenoid this is the wire to disconnect for the remote switch to be used

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and finally with the switch connected

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connect the remote starter switch to BAT +

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I'm using a Magnetic tray to hold GP's

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GP 1-7 on Left 2-8 on Right

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cyl 4 & 6 look damp here pointing to #4

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close up 1-7

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Close up 2-8

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I've got video coming as well so stay tuned for more to come!

Thanks for looking

Al

 

[riotwarrior]

WARNING

Always purge your block/engine prior to connecting a comp tester, using the starter only and FSS disconnected, turn over engine a few times to blow out any fuel or fluid in the cylinders, this can prevent any problems when testing.

KEEP HANDS AND FACE AWAY FROM GP HOLES WHEN PURGING!!!!!
Once you purge the engine then follow along with what I've done if you choose to


Here is my PRE comp test video, and take notice about the 1:55 mark and watch close!

http://youtu.be/JNfys2W7WU0

Notice that nice geyser of fluid out my #4 cylinder?????

Here is the first comp test of Cyl # 1 and I've discovered my comp tester has bad schrader valve in it so that's why it bleeds down. Two more tries to get a valve that works! DOH!!!! Guess got to pick up some new ones eh??

I speak of a valve not working or sticking open, I'm referring to the schrader valve in the tip of the compression tester adapter. It is similar to a tire valve but constructed differently to withstand oil/grease/etc and higer pressures of and engine compression tester. I AM NOT TALKING ABOUT THE INTAKE OR EXHAUST valves in the engine it's self
http://youtu.be/Ol1-YUamCeo

Here is the redux of the comp test, and for sake and ease of doing the test for a video instructional, I elected to do this on #2 cylinder, it is much easier to access for me for demonstration purposes.
http://youtu.be/RbUai2sTssA

As mentioned in my video, and I'll reiterate it here....

I always look for and observe the initial or primary pulse on the comp tester gauge and record that along with accumulated compression. It helps to see how tight the engine is and how much compression you build in a few strokes, usually it is 5-7 pulses for a complete test to indicate max cranking compression. Now remember folks this is a method I use which produces data I interpret and work with.

The key is to always do the tests the same way! Consistency is the key to attaining usable results.

I did not feel it important enough to show a video for each cylinder and such as do one do all the same right?

Thanks

Al

GOOD INFO HERE, most of which I neglected to add so I'll just throw in your comment!

Excellent tech. A couple items on the compression tester for people who haven't done this before. ALWAYS relieve the pressure before popping the quick connect or wear some ear plugs and have lots of spare o-rings on hand. It will sound like a rifle going off and blow the o-ring to hell. The hole where the glow plugs go are like octo-mom's belly button. Make sure you give them a good blast from the compressor to get all the lint, old gasket pieces, spare change and small animals out of there before pulling the glow plugs.

Thanks for the post dgr!!!

Al

 

[riotwarrior]

Now onto more meat and potatoes!!!!

I have completed my test of my engine and the results are as follows;

CYLINDER

1, 200/450 2, 200/410

3, 250/440 4, 0

5, 220/450 6, 220/440

7, 230/450 8, 230/450.

This seems quite nice other than cylinder 4 being ZERO ugh? Now I'm not sure it's a head gasket as I had thought between cylinders.

 

[riotwarrior]

Just popped the drivers side valve cover and wow, am I ever glad I did, Schmeg and lots of it...Need to get some Auto RX and LOTS of it wow this *****'s like tar in the valve cover and this issue be it a HG or what have you is a blessing cause now I know the insides...are dirty dirty dirty!

That's ok I can deal with it...lots of oil/filter changes and AUTO RX I suppose now!

Back to what I'm working on.

Just to be certain that the 0 compression on #4 cyl was indeed due to something like HG and not a dropped valve etc, I removed the valve cover and inspected.

Here are the pics, and vid of said inspection.

Clearly extremely dirty inside! This must be from idling on a log landing as a service truck for extended periods of time!

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Ya really freakin dirty

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And here is the functioning valvetrain all cylinders functioning
http://youtu.be/ASYR9j9bHIU

Thus I'm still thinking HG or...cracked head as the only other options for coolant leakage.

Thanks for looking and more to come...maybe other TECH 101's

Al

 

[icanfixall]

Nice **** insides Al.. Wow thats ugly as a 2am last call.... Thats a great job for Auto RX for sure. Now for something many need to look at on the pic number two. See the two bolts that holds the intake to the head.. See the number 2 cast into the head. Good... Now a'll know where to look for the cylinder numbers instead of guessing what they are. Members that have rented my timing meters have connected to all kinds of cylinders thinking they were on number one or four. Some of you will have to clean off the intake to see these numbers but at least now you have actually seen where they are. This message is not to imbarrass anyone. We al make mistakes. I made a big one a few weeks ago timing dragrags truck. I couldn't get my repaired meters to work correctly. So I went home and tested all my meters.. Well none of them worked... WTH is going on. They are sitting here in a cool dry place and they are broken. So I start testeing them again and finally figured out I was pressing the wrong rocker switch... Imagine that. Me that knows more than most. That has taken these meters apart and replaced parts. Talked to the only repair guy in the country has made a mistake... Well it happens.

 

[dgr]

Excellent tech. A couple items on the compression tester for people who haven't done this before. ALWAYS relieve the pressure before popping the quick connect or wear some ear plugs and have lots of spare o-rings on hand. It will sound like a rifle going off and blow the o-ring to hell. The hole where the glow plugs go are like octo-mom's belly button. Make sure you give them a good blast from the compressor to get all the lint, old gasket pieces, spare change and small animals out of there before pulling the glow plugs.

Al, did you push down on the pushrods to check the lifters while you were in there? Is there anything else someone could do from the top for diagnosis before you get further into the engine? What's the chance of you showing us all how to pull the retainers on a valve spring and check the valve guide wear from the top? You think all that nasty build up is blow by through the valve seals burning oil in the valve covers? Oh yeah, buy some auto-rx already. That's nasty in there.

 

[riotwarrior]

Excellent tech. A couple items on the compression tester for people who haven't done this before. ALWAYS relieve the pressure before popping the quick connect or wear some ear plugs and have lots of spare o-rings on hand. It will sound like a rifle going off and blow the o-ring to hell. The hole where the glow plugs go are like octo-mom's belly button. Make sure you give them a good blast from the compressor to get all the lint, old gasket pieces, spare change and small animals out of there before pulling the glow plugs.

Thanks and I threw a quoted copy of your post in the thread with comp test videos. I tend to forget at times to throw in some of the more simple instructions that I just do as a matter of cause, knowing to do it and writing every single thing at times gets long in tooth and you tend to forget some of the procedural things and prep and sometimes safety stuff when writing it out. It is helpful replies like this that help make these Tech 101's what they are Thanks!

Al, did you push down on the pushrods to check the lifters while you were in there? Is there anything else someone could do from the top for diagnosis before you get further into the engine? What's the chance of you showing us all how to pull the retainers on a valve spring and check the valve guide wear from the top? You think all that nasty build up is blow by through the valve seals burning oil in the valve covers? Oh yeah, buy some auto-rx already. That's nasty in there.

Nope no pushy down on pushrods, they push up not down buwa ha ha ha ha...no I did not bother with that I was more or less looking for function of valve train and observing for broken or missaligned parts and pushrods etc. Everything seemed to be functioning as it should albeit dirtier than it should

U want me to do what? Pull some rockers and then valve spring retainers and show how to inspect valve guides for wear from the top end? *** over why don't you do it? I suppose I could do that I just didn't want to be dropping valves however I'll see what I can do. This would be contingent on me being able to get the valve springs to compress properly on the head with head on engine. I'm not sure I've got the tool for that,

Since I'm pulling the head anyway, I suppose I can give it my best shot and eh what do I have to loose?

I'll do it on a cylinder with compression in case there is a big hole in piston #4 and valve falls down into pan...ya that's my reasoning, not that a piston with a hole would actually stay in the engine and that engine in the truck nooo

Stay tuned for a valve check guys...per request!

Al

 

[laserjock]

Al, what is the size and thread pitch of the glow plug so that whatever kit I buy I can make sure it has the appropriate adapter?


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[icanfixall]

The glow plug thread is metric and so is the injecter thread. Glows are a M10x1 or sae j5480 The injecter is a 24mmx2.0 thread.

 

[GOOSE]

Good progress Al. I am leaning towards head gasket. I had a 2" crack in my cylinder wall and still mustered 230lbs of compression. Best of luck and keep us posted.

 

[icanfixall]

I really can't see this issue being a cracked head but.. Its a possible too. Just not as probable as a head gasket. But then the question of why a head gasket lets go is something that needs to be looked at too. Al, Doing the oil cooler with the rivers side head off is about the beat idea when your that deep into it. No easier time to remove that log o fun and **** either... The exhaust manifold is out of the way as is the head. Just 8 bolts and lift it up and out. Much easier to clean off the block too. Nothing worse for me than cleaning off gasket material laying on my back. Gravity really sucks then and my face usually has gunk covering it.
When you get the head off it might be a good idea to straight edge and feeler gauge the blown area checking for a low spot on the block too. Using some spray Hilomar on both sides of th ehead gasket will take up the low places that are less than a hundred thousands low on the block too. If that stuff can seal up the Rolls Royce jet engines then it will seal up our idi engines. Back in the 60s and 70s bikes like BSA and Triumph could not make a aluminum casting that was not pourous so they leaked oil no matter what. They used a special gasket sealer called Red Hermatite. It made the metal to metal seals finally work. But oil would still leak out of the castings. Those bikes always marked their spot...

 

[riotwarrior]

Just checked my Ford manual and unfortunately they do not offer up information on compression test readings.

They only state that the lowest cylinder has to be 75% of the highest cylinder.

Hmm...so 410 lbs as lowest cause 0 is just nfg as a reading puts it at 91% of 450 lbs...not a bad spread,

Now on to determining if these readings are good or not or what the stock reading would be.

Damn that PMO something big...wish they would put the actual rated pressure min and max.

Oh well I'm OK with what I've got so far.

Al

 

[GOOSE]

410-450psi is VERY GOOD. My engine is just about broken in, I should give you a reference.

 

[icanfixall]

My engine is 530 lbs of cranking pressure with the gear reduction starter from Mitsubishi. I recall something like 240 is concidered as junk.

 

[riotwarrior]

Ya I don't burn oil really at all, small leaks that are now being taken care of with this repair. I'm thinking I've got a strong runner here that just needs a good AUTO RX treatment or two or THREE and fresh HG and maybe valve job.

I go look at a truck later with a reman 7.3 in it with sic/dead??? E4OD F250 4x that I know needs all new bj's on front end so could be had cheap maybe...trade deal perhaps...no title as was put in some GF's name and she's pissed at owner.. Could be win win it's an OBS too

Hmm...*** to do???

I'll post pics of heads off later maybe...hard to say!

Al