PeachParts Mercedes-Benz Forum

PeachParts Mercedes-Benz Forum (http://www.peachparts.com/shopforum/)
-   Diesel Discussion (http://www.peachparts.com/shopforum/diesel-discussion/)
-   -   DIY OM603 head pressure test - head good? (http://www.peachparts.com/shopforum/diesel-discussion/393591-diy-om603-head-pressure-test-head-good.html)

ah-kay 06-09-2018 01:54 PM

DIY OM603 head pressure test - head good?
 
2 Attachment(s)
Well, I got this head from a junk yard. It was removed by others and left next to the car. I bought it not noticing the cracks between the valves in 3 cylinders. May be it was the reason that it was left there. I decided to challenge myself and pressure test the head for fun. I used coins to block all coolant passages with JB weld, block the big coolant outlet by putting a plate there and screw the hose connector back on. Actually it is quite easy to do and spend very little time. Submerge the head in water and pressurize the head to 50psi. NO BUBBLES. It also holds vacuum if I pump it with a vacuum pump. All in all, I think it is good. The only shortcoming is I did not use hot water. What do you guys think? Good to install?

btw: you can notice the cracks between valves if you look closely. It doesn't seem to matter in this case, contrary to conventional beliefs.

jay_bob 06-09-2018 02:27 PM

I suspect that under the dynamics of a running engine things are quite different. Remember you’re dealing with 300-350 psi of compression (ideally) and the head is heated to approximately 80 C/180 F.

I think these two factors are what make head cracks leak, not hitting it with 50 psi air in ambient temperature water.

My opinion which is probably worth about equal to the $0.42 I see glued to that head...

ah-kay 06-09-2018 03:13 PM

The professional is also pressuring the head to Max 400kpa which is about 58psi. The condition is similar except in hot water. I ramped it to 80psi and still no bubbles. I may be wrong but I am comfortable with my testing.

Diseasel300 06-09-2018 05:26 PM

Cracks between valves = junk. It isn't a question of will it leak, it's how badly does it leak? The pressure in the cylinder is much higher than the 350-400PSI of compression when the fuel ignites.

tjts1 06-09-2018 06:27 PM

Is this a #14 head? Take close-up pics of the space between the valves and prechamber on cyl 4, 5 and 6.

jt20 06-09-2018 08:01 PM

Visible cracks do not always mean they go all the way through.

It could be fine, but certainly not great, and is way more likely to crack further.

Temperature is very important for this test. I would not install it without testing at near boiling temp.

Thats a lot of work.

ah-kay 06-09-2018 10:20 PM

Quote:

Originally Posted by jt20 (Post 3820081)
Visible cracks do not always mean they go all the way through.

It could be fine, but certainly not great, and is way more likely to crack further.

Temperature is very important for this test. I would not install it without testing at near boiling temp.

Thats a lot of work.

I like your comments. It is a #14 head.

ah-kay 06-09-2018 10:24 PM

Quote:

Originally Posted by Diseasel300 (Post 3820034)
Cracks between valves = junk. It isn't a question of will it leak, it's how badly does it leak? The pressure in the cylinder is much higher than the 350-400PSI of compression when the fuel ignites.

I beg to differ. I expect any crack, no matter how minute, would show bubbles at 80psi.

tjts1 06-09-2018 11:01 PM

Quote:

Originally Posted by ah-kay (Post 3820094)
I like your comments. It is a #14 head.

You're playing with fire. If it's not leaking yet it will eventually. If you can't see any cracks on close inspection the only real test is to run it on the engine and see if it pressurizes your cooling system. The later #17 and up heads are substantially redesigned. The deck of the head is much thicker. I wouldn't bother with a "good" #14 head.

Diseasel300 06-09-2018 11:20 PM

Quote:

Originally Posted by ah-kay (Post 3820095)
I beg to differ. I expect any crack, no matter how minute, would show bubbles at 80psi.

Hey, your time, your money. You do what you want. Considering how the #14 heads are the most common to leak and cracks in a casting are NEVER a good thing, whatever...

Go ahead and throw it on the car and see how it works. At best you'll get some life out of it before it starts vapor locking the cooling system. At worst you'll have wasted a head gasket, time, and money on a POS head. Your call...

ah-kay 06-10-2018 12:10 AM

Quote:

Originally Posted by Diseasel300 (Post 3820112)
Hey, your time, your money. You do what you want. Considering how the #14 heads are the most common to leak and cracks in a casting are NEVER a good thing, whatever...

Go ahead and throw it on the car and see how it works. At best you'll get some life out of it before it starts vapor locking the cooling system. At worst you'll have wasted a head gasket, time, and money on a POS head. Your call...

I have done a number of head replacements and they are all #14. Please please don't make out #14 like a monster. There are still a lot of om603 engine running around with#14. I have put heads with hairline cracks back on and they run Ok. I decide to do a diy pressure test on this one and I find it to be good, in my opinion. I really can't see problem with this head if it holds 80psi.

I understand it is my car, my time and my money. I just want to share my experience on how-to with some improvisation. I appreciate all your comments.

Diseasel300 06-10-2018 12:32 AM

I'm not knocking the #14 head. I'm running one on my own car. When the head came off for valve work, it was inspected for cracks and pressure tested. It passed and got re-used. I'm certainly not afraid of a sound #14 head and I think the paranoia surrounding them is way overblown.

THAT SAID, cracks are NOT a good sign on the #14 casting, if it isn't leaking now, it will be soon. It's a lot of effort and time to pull and replace the head, not a job to look forward to.

ah-kay 06-10-2018 01:00 PM

These are links which show how pressure test is done. As long as there is no bubbles, the head is good to go. It may not be necessary to test with hot water. Please understand hairline cracks do not mean cracked head. One word of caution for any one who tries this. Wear safety goggles. If the glued coin popped under pressure, it can fly anywhere.

https://youtu.be/A26KfDj6wAM
https://youtu.be/VJL-hcC_CBA
https://youtu.be/x_OHmyTYDBQ

tjts1 06-10-2018 01:15 PM

Quote:

Originally Posted by ah-kay (Post 3820183)
These are links which show how pressure test is done. As long as there is no bubbles, the head is good to go. It may not be necessary to test with hot water. Please understand hairline cracks do not mean cracked head. One word of caution for any one who tries this. Wear safety goggles. If the glued coin popped under pressure, it can fly anywhere.

https://youtu.be/A26KfDj6wAM
https://youtu.be/VJL-hcC_CBA
https://youtu.be/x_OHmyTYDBQ

The problem with the #14 head isn't coolant
Leaking into the CC, it's combustion leaking into the cooling system. That's over 1000psi which you're not going to simulate with a pressure test like that. On my bad #14 head I never needed to top off the coolant yet the hoses were bulging and smoke was blowing out of the coolant bottle. Any crack in a #14 head is bad.

This is what a bad #14 head looks like.
cyl 4
https://i.imgur.com/e0Y3RKJ.jpg?2

cyl 5
https://i.imgur.com/Fds8gj9.jpg?2

cyl 6
https://i.imgur.com/vy1dBEz.jpg?2

ah-kay 06-10-2018 01:38 PM

Quote:

Originally Posted by tjts1 (Post 3820187)
The problem with the #14 head isn't coolant
Leaking into the CC, it's combustion leaking into the cooling system. That's over 1000psi which you're not going to simulate with a pressure test like that. On my bad #14 head I never needed to top off the coolant yet the hoses were bulging and smoke was blowing out of the coolant bottle. Any crack in a #14 head is bad.

With due respect you may be right. We will see.


All times are GMT -4. The time now is 01:01 AM.

Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2018, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2018 Pelican Parts, LLC - Posts may be archived for display on the Peach Parts or Pelican Parts Website