DIY OM603 head pressure test - head good? - Page 3 - PeachParts Mercedes-Benz Forum

97 SL320 · #31 06-11-2018, 10:36 AM

Quote:

Originally Posted by ah-kay

Shall I take it to a professional and ask them to check with flourescent dye?

Dye checking is for locating cracks that are not visible to the eye, it will not determine crack depth.

As for air leak checking, scroll down to " Pressure Testing ". Goodson is a large engine rebuilder supply house.

https://goodson.com/blogs/goodson-gazette/holes-in-your-head-or-the-fine-art-of-crack-detection

Quote:

First of all, the head being tested needs to be completely clean. You will attach a special block-off plate to the head to seal off the water passages, then pump pressurized air into the head through an air line inserted into a water port. Some sources will tell you to use about 60 psi, but in my experience, 20 to 25 psi is adequate. Some heads have core plugs pressed into them and these will blow out at 60 psi. It’s not only an inconvenience, it’s a safety hazard.

This system can test up to 800 KPA ( 116 PSI )

Cylinder Head Block Tester - Quality Power Products

AERA is _ The _ engine rebuilders definitive source for tech info. Note near the top of page 2 they are using 50 PSI to test for coolant leaks on a 15 L diesel.

http://www.engineprofessional.com/TB/TB042517-2.pdf

tjts1 · #32 06-11-2018, 10:40 AM

Do any of those 15L diesels they test for leaks have aluminum heads?

ah-kay · #33 06-11-2018, 11:46 AM

Quote:

Originally Posted by 97 SL320

Dye checking is for locating cracks that are not visible to the eye, it will not determine crack depth.

As for air leak checking, scroll down to " Pressure Testing ". Goodson is a large engine rebuilder supply house.

https://goodson.com/blogs/goodson-gazette/holes-in-your-head-or-the-fine-art-of-crack-detection

This system can test up to 800 KPA ( 116 PSI )

Cylinder Head Block Tester - Quality Power Products

AERA is _ The _ engine rebuilders definitive source for tech info. Note near the top of page 2 they are using 50 PSI to test for coolant leaks on a 15 L diesel.

http://www.engineprofessional.com/TB/TB042517-2.pdf

Thanks for the info from a professional. I am more confident than ever that the head from jy will hold up. I did not remove it from the junk car, someone removed and abandoned it after seeing the cracks. It's either he was missing out or my lucky day. We will see.

jay_bob · #34 06-11-2018, 12:41 PM

I'm watching this too to see how it ends up.

Would be very a interesting data point in the OM603 experience, if a visibly cracked #14 head, holds 50 psi in an ambient temperature water bath, and ends up being serviceable.

Good luck and be sure to let us know how it worked out. Lots of people condemning #14s for small cracks like in your photos, so if your test works out well long term that could be a very good thing.

barry12345 · #35 06-11-2018, 01:35 PM

Cars are disgarded for reasons. This could be why that one in the wreckers was.. If you are going to persist. Go back to the car to see if there is anyway to contact the last owner. Some people leave papers in cars they send in and perhaps even licence plates in certain states.

Personally I suspect the cracks in these heads act like one way valves. Under high combustion pressures they admit pressure to the coolant passages. Under low pressure they no longer leak.

This is kind of verified by 603 engines with cracked heats still have coolant system pressure the next morning as a test. Logically to me if they also leaked at low pressure. There would be no retained pressure in the coolant system the next day. The pressure input could be very high also but any accumulating above the radiator cap limit. Would just be relieved by it.

I am not suggesting what you should do. Yet if I lived in your part of the country myself I would look for a newer head. Primarily because the odds of finding one are very high there compared to my region. Those cracks may also be a good reason for an engine to run hot.

Also other members could comment. We have quite a few members that have changed cracked 603 heads. Was there coolant in those cylinders that had the cylinders with the cracks in their heads? If my thoughts are right in many perhaps none was observed.

Since of course I only have limited abilities and experience. I am almost positive that you can find a rebuilder of Mercedes heads in your general area. The most famous one is even in your state I believe.

My suspicion is they will tell you that any cracks found of your type existing in that number fourteen head. They probably do not even bother testing it. Simply because it is what it is. A number fourteen head that has cracks. In addition all cracks of that type you have always create issues they found.

There are heads with real obvious cracks like the early Volkswagon water cooled diesel engines. The first one I pulled scared me . Until I found out they were normal unless really wide. Every cylinder had them as well. Yet they never caused me a problem. We pulled a lot of those heads to change failing head gaskets.

Plus if by some odd chance my thoughts are correct. They may have found out they do not leak test in the conventional way a long time ago. Again just a suspicion of mine. Unless the cracks really open up. The hot water expands the alloy head of course. It is just not restrained when it cools down like it would be to some extent when mounted on the block.

Also remember that an alloy head on a cast iron block has movement in relation to the cast iron block. So in service this can actually manipulate the cracks slightly. Yes it slides on the head gasket but the forces are still substantial on the casting. Over the years I have thought there are perhaps many contributors to the high failure rate of these heads anyways. Just food for thought.

97 SL320 · #36 06-11-2018, 01:47 PM

Quote:

Originally Posted by tjts1

Do any of those 15L diesels they test for leaks have aluminum heads?

Probably not, but the 2001 + GM ( Isuzu ) Duramax has aluminum heads as does the Ford Power stroke 6.7 from 2011 + .

I don't have any testing procedures for these. If someone is running super high boost / load, super small crack could be unfindable with conventional methods but this would be a rarity.

ah-kay · #37 06-11-2018, 04:02 PM

Quote:

Originally Posted by barry12345

Cars are disgarded for reasons. This could be why that one in the wreckers was.. If you are going to persist. Go back to the car to see if there is anyway to contact the last owner. Some people leave papers in cars they send in and perhaps even licence plates in certain states.

Personally I suspect the cracks in these heads act like one way valves. Under high combustion pressures they admit pressure to the coolant passages. Under low pressure they no longer leak.

This is kind of verified by 603 engines with cracked heats still have coolant system pressure the next morning as a test. Logically to me if they also leaked at low pressure. There would be no retained pressure in the coolant system the next day. The pressure input could be very high also but any accumulating above the radiator cap limit. Would just be relieved by it.

I am not suggesting what you should do. Yet if I lived in your part of the country myself I would look for a newer head. Primarily because the odds of finding one are very high there compared to my region. Those cracks may also be a good reason for an engine to run hot.

Also other members could comment. We have quite a few members that have changed cracked 603 heads. Was there coolant in those cylinders that had the cylinders with the cracks in their heads? If my thoughts are right in many perhaps none was observed.

Since of course I only have limited abilities and experience. I am almost positive that you can find a rebuilder of Mercedes heads in your general area. The most famous one is even in your state I believe.

My suspicion is they will tell you that any cracks found of your type existing in that number fourteen head. They probably do not even bother testing it. Simply because it is what it is. A number fourteen head that has cracks. In addition all cracks of that type you have always create issues they found.

There are heads with real obvious cracks like the early Volkswagon water cooled diesel engines. The first one I pulled scared me . Until I found out they were normal unless really wide. Every cylinder had them as well. Yet they never caused me a problem. We pulled a lot of those heads to change failing head gaskets.

Plus if by some odd chance my thoughts are correct. They may have found out they do not leak test in the conventional way a long time ago. Again just a suspicion of mine. Unless the cracks really open up. The hot water expands the alloy head of course. It is just not restrained when it cools down like it would be to some extent when mounted on the block.

Also remember that an alloy head on a cast iron block has movement in relation to the cast iron block. So in service this can actually manipulate the cracks slightly. Yes it slides on the head gasket but the forces are still substantial on the casting. Over the years I have thought there are perhaps many contributors to the high failure rate of these heads anyways. Just food for thought.

One way valve out of a block of aluminum? Wow, that is news to me. Air will find a way to escape, in cast iron or aluminum. So I would discount the head material. If you can't find a leak at 50psi then I don't know what will. I ramped it to 80psi and no bubbles. My existing head is so bad that coolant will leak into the combustion chamber and hydrolock the engine. I will repeat the same test if I have time when I swap it out with this jy head.

Diseasel300 · #38 06-11-2018, 04:38 PM

Quote:

Originally Posted by ah-kay

I did not remove it from the junk car, someone removed and abandoned it after seeing the cracks. It's either he was missing out or my lucky day. We will see.

We will indeed. I wouldn't have pulled a 14 head unless I was desperate and didn't have time to find a 17 or later.

Quote:

Originally Posted by 97 SL320

Probably not, but the 2001 + GM ( Isuzu ) Duramax has aluminum heads as does the Ford Power stroke 6.7 from 2011 + .

A lot of time elapsed between 1986 and 2001. Any manufacturer with a brain would have learned from Mercedes' weakness with the original #14 casting. Cracks on later castings or on other manufacturers' designs aren't as critical as they are with the #14 603 head.

Quote:

Originally Posted by ah-kay

One way valve out of a block of aluminum? Wow, that is news to me. Air will find a way to escape, in cast iron or aluminum. So I would discount the head material. If you can't find a leak at 50psi then I don't know what will. I ramped it to 80psi and no bubbles. My existing head is so bad that coolant will leak into the combustion chamber and hydrolock the engine. I will repeat the same test if I have time when I swap it out with this jy head.

Most of the 14 head failures don't leak coolant. They leak combustion gas into the coolant jacket and pressurize it causing overheating. The typical telltale sign is cracks between the valve seats when the head is pulled. One is bad enough, having 3 of the 6 cracked suggests that engine had a rough life or the casting in question is particularly weak.

ah-kay · #39 06-11-2018, 04:52 PM

Quote:

Originally Posted by Diseasel300

Most of the 14 head failures don't leak coolant. They leak combustion gas into the coolant jacket and pressurize it causing overheating. The typical telltale sign is cracks between the valve seats when the head is pulled. One is bad enough, having 3 of the 6 cracked suggests that engine had a rough life or the casting in question is particularly weak.

When a head is cracked, it means breached passage. Water will go to chamber, gas wiil go to coolant. It is just a matter of how much. I think we agree to disagree. Just leave it at that.

Diseasel300 · #40 06-11-2018, 04:58 PM

Quote:

Originally Posted by ah-kay

When a head is cracked, it means breached passage. Water will go to chamber, gas wiil go to coolant. It is just a matter of how much.

What an idiotic statement. A crack in a cylinder head can most definitely allow combustion products into the cooling system, but not coolant into the cylinder. It's very well documented on the 14 casting. The issue comes from a head design that isn't structurally stiff enough, allowing stress cracks. A micro fissure in the aluminum material subjected to high heat and extreme pressure from the combustion chamber can and will leak into the coolant jacket.

Just because you don't want to hear or believe it doesn't make it wrong.

tjts1 · #41 06-11-2018, 05:21 PM

Is this really worth arguing over? Let him install the head and let's see what happens. It'll be an interesting experiment no matter what the results. I hope the OP takes some closeup pics of the cracks before installing it.

Hit Man X · #42 06-11-2018, 05:47 PM

It's the pleats.

97 SL320 · #43 06-11-2018, 05:54 PM

Quote:

Originally Posted by Diseasel300

A crack in a cylinder head can most definitely allow combustion products into the cooling system, but not coolant into the cylinder.

Only if the crack is opening under combustion pressure. It is possible but not common and I've never seen on in person or discussed in a trade magazine. I'm basing this on decades of real shop experience across many makes.

The world is made up of more than friction-less pulleys and ideal gasses. ( Think about the ideal gas law for a bit, what I state is more subtle than you think. )

As for checking for a combustion to coolant leak with sub 90 PSI air, read this

M104.980 too much radiator hose pressure?

This links to a rad pressure on an aluminum head M104. Post 18 says

Quote:

A leak down test confirms it. I went in order of 1-5-3-6-2-4 and 3 was the one that was leaking into the cooling system. Pressurized the cylinder at TDC with around 30psi and I heard bubbles in the coolant reservoir.

Have a look at the pic, the fire ring on 3 is intact and only slightly dark on the drivers side. Granted we can see the underside of the gasket but gee, our guy found the leak at 30 PSI. Number 1 is at bottom.

Diseasel300 · #44 06-11-2018, 06:17 PM

That's cute comparing a blown head gasket to a cracked head. Nice try, but no. The M104 also has nowhere near the cylinder pressures of the turbo 603, nor does it have a weak casting design like the #14 head. Sometimes it pays to be familiar with the specific issue at hand rather than using generic wisdom. In any other case on any other engine or cylinder head I'd be in agreement, but not this time.

barry12345 · #45 06-11-2018, 06:19 PM

Coolant was getting into the cylinder in the example posted. If the hood is still present and even if not. Could you not have a look at that engines cylinders? That the used head came from?

It would not be conclusive if a cylinder was not washed down. Actually steam cleaned. At the same time if one appeared to be. You then have a solid indication of not to risk using the head.

When I mentioned can act like a one way valve. Molecular size and charactaristics of elements and materials do enter into the picture at times as well. You probably remember when synthetic oil was introduced. People were screaming about their engines leaking out. Besides any solvent type action. The base of synthetic oil was probably involved in another way. In any event the synthetic base was modified and the problem drastically reduced. You seldom hear of it anymore.

A mans repair approaches to things are his own business. No matter how sorrid or counterproductive they may be or may not be. They are his. In this case sure it may work out. Or may not. Your gamble.

I understand this. There is only one sure thing. The odds do not favor this approach. Still you could luck out and say I told you so. Personally I would like to see it work out than not. Say it even did. Would you be thinking of the cracks all the time and always waiting for something. They are not going to self heal up.