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#1
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DIY OM603 head pressure test - head good?
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.
__________________
Not MBZ nor A/C trained professional but a die-hard DIY and green engineer. Use the info at your own peril. Picked up 2 Infractions because of disagreements. NOW reversed. W124 Keyless remote, PM for details. http://www.peachparts.com/shopforum/mercedes-used-parts-sale-wanted/334620-fs-w124-chasis-keyless-remote-%2450-shipped.html 1 X 2006 CDI 1 x 87 300SDL 1 x 87 300D 1 x 87 300TDT wagon 1 x 83 300D 1 x 84 190D ( 5 sp ) - All R134 converted + keyless entry. |
#2
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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...
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The OM 642/722.9 powered family Still going strong 2014 ML350 Bluetec (wife's DD) 2013 E350 Bluetec (my DD) both my kids cars went to junkyard in 2023 2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles) 2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles) 1998 E300DT sold to TimFreeh 1987 300TD sold to vstech |
#3
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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.
__________________
Not MBZ nor A/C trained professional but a die-hard DIY and green engineer. Use the info at your own peril. Picked up 2 Infractions because of disagreements. NOW reversed. W124 Keyless remote, PM for details. http://www.peachparts.com/shopforum/mercedes-used-parts-sale-wanted/334620-fs-w124-chasis-keyless-remote-%2450-shipped.html 1 X 2006 CDI 1 x 87 300SDL 1 x 87 300D 1 x 87 300TDT wagon 1 x 83 300D 1 x 84 190D ( 5 sp ) - All R134 converted + keyless entry. |
#4
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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.
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#5
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Is this a #14 head? Take close-up pics of the space between the valves and prechamber on cyl 4, 5 and 6.
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CENSORED due to not family friendly words |
#6
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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. |
#7
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Quote:
__________________
Not MBZ nor A/C trained professional but a die-hard DIY and green engineer. Use the info at your own peril. Picked up 2 Infractions because of disagreements. NOW reversed. W124 Keyless remote, PM for details. http://www.peachparts.com/shopforum/mercedes-used-parts-sale-wanted/334620-fs-w124-chasis-keyless-remote-%2450-shipped.html 1 X 2006 CDI 1 x 87 300SDL 1 x 87 300D 1 x 87 300TDT wagon 1 x 83 300D 1 x 84 190D ( 5 sp ) - All R134 converted + keyless entry. |
#8
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I beg to differ. I expect any crack, no matter how minute, would show bubbles at 80psi.
__________________
Not MBZ nor A/C trained professional but a die-hard DIY and green engineer. Use the info at your own peril. Picked up 2 Infractions because of disagreements. NOW reversed. W124 Keyless remote, PM for details. http://www.peachparts.com/shopforum/mercedes-used-parts-sale-wanted/334620-fs-w124-chasis-keyless-remote-%2450-shipped.html 1 X 2006 CDI 1 x 87 300SDL 1 x 87 300D 1 x 87 300TDT wagon 1 x 83 300D 1 x 84 190D ( 5 sp ) - All R134 converted + keyless entry. |
#9
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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.
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CENSORED due to not family friendly words |
#10
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Quote:
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... |
#11
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Quote:
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.
__________________
Not MBZ nor A/C trained professional but a die-hard DIY and green engineer. Use the info at your own peril. Picked up 2 Infractions because of disagreements. NOW reversed. W124 Keyless remote, PM for details. http://www.peachparts.com/shopforum/mercedes-used-parts-sale-wanted/334620-fs-w124-chasis-keyless-remote-%2450-shipped.html 1 X 2006 CDI 1 x 87 300SDL 1 x 87 300D 1 x 87 300TDT wagon 1 x 83 300D 1 x 84 190D ( 5 sp ) - All R134 converted + keyless entry. |
#12
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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. |
#13
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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
__________________
Not MBZ nor A/C trained professional but a die-hard DIY and green engineer. Use the info at your own peril. Picked up 2 Infractions because of disagreements. NOW reversed. W124 Keyless remote, PM for details. http://www.peachparts.com/shopforum/mercedes-used-parts-sale-wanted/334620-fs-w124-chasis-keyless-remote-%2450-shipped.html 1 X 2006 CDI 1 x 87 300SDL 1 x 87 300D 1 x 87 300TDT wagon 1 x 83 300D 1 x 84 190D ( 5 sp ) - All R134 converted + keyless entry. |
#14
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Quote:
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 cyl 5 cyl 6
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CENSORED due to not family friendly words |
#15
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Quote:
__________________
Not MBZ nor A/C trained professional but a die-hard DIY and green engineer. Use the info at your own peril. Picked up 2 Infractions because of disagreements. NOW reversed. W124 Keyless remote, PM for details. http://www.peachparts.com/shopforum/mercedes-used-parts-sale-wanted/334620-fs-w124-chasis-keyless-remote-%2450-shipped.html 1 X 2006 CDI 1 x 87 300SDL 1 x 87 300D 1 x 87 300TDT wagon 1 x 83 300D 1 x 84 190D ( 5 sp ) - All R134 converted + keyless entry. |
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