Please tell me I don't need to resurface the block

greiswig · **Posted:** Sun Sep 07, 2014 3:14 pm

Grrrr. I finally got to cleaning the block surface, and now I am wondering about some of the corrosion pitting I am seeing.

I have read many conflicting opinions about using something like Hylomar in a case like this to try to fill the gap in. The MLS gasket has basically nothing on its surface that seems able to take up any kind of gap at all. I really don't want to pull the block, because of all the additional "well, as long as I'm in this far I should replace the____" expenses on a project that is already beyond my ability to afford.

Here is cylinder #2, the one that had coolant in it. This looks like the likely path.

And here is cylinder #1 for comparison. Both sets of pits are about equal in depth. But there wasn't coolant getting in to #1.

Note also that the channel doesn't appear to cross the sleeve lip in either case, so. I still am not clear on how coolant got into the cylinder.

It seems like something like Hylomar is made for just this kind of situation. But some people are vehement that it will do more harm than good. Any input from the tech-savvy mechanics on this board?

geordi · **Posted:** Sun Sep 07, 2014 4:05 pm

Ok... The gasket is laminated steel. The sealing surfaces are flat solid metal, either steel or aluminum. There isn't a "fire ring" boundary in the head gasket around each cylinder, the clamping force is the only thing that creates or maintains the seal.

Hylomar (This is a new product to me, but I found it is made by Permatex) says that it never dries OR CURES. To me, that is not a benefit in this situation, as it now will be a barrier layer between the clamping surfaces, even if squeezed to one molecule thick, it still is there and could be subject to pressure migration and creation of another pathway for combustion gasses to escape.

If you really want to use something to help the system seal, I would suggest some RTV black or red (whichever has the higher temperature limit) and draw a thin ring around each cylinder individually to create your own silicone fire ring.

That said, the system is designed to not have anything, so it really will be your choice here. I'm a fan of more sealing rather than less, so I'd probably do the silicone if this were my CRD.

flman · **Posted:** Sun Sep 07, 2014 4:43 pm

Use the Permatex copper coat if you have any doubts.

greiswig · **Posted:** Sun Sep 07, 2014 4:44 pm

Thanks, geordi.

Hylomar is supposedly a little better than the Permatex Copper spray-on sealer, at least according to some. But i can't even find the spray version of Hylomar.

I'm in favor of a better seal anywhere I can get it. I don't want to have to do this job again until if/when I overhaul the whole engine. So anything that helps seal in spite of small surface irregularities that I can't get rid of without machining the block...I'd like to do that unless it is really going to hurt in the long run.

To me, it looks like if I were going to put silicone somewhere, it would be around the coolant passages on the block side. Maybe also around where the sleeve meets the block, because that gap there makes me nervous and it is far from flat...and where did the coolant go that made the channel up to that point? Worst case, it went into the crankcase past the sleeve. Another scenario you don't want happening.

greiswig · **Posted:** Sun Sep 07, 2014 4:45 pm

flman wrote:

Use the Permatex copper coat if you have any doubts.

Have you used it successfully on a diesel head gasket? How long did it seem to last? And was the pitting as bad as what my pics show?

geordi · **Posted:** Sun Sep 07, 2014 6:17 pm

Split your old head gasket. I suspect that you will find your coolant passage in between several of the leaves of the gasket, and THAT is how the coolant migrated when the clamping from the bolts failed. If I were designing this, I might retain the same laminated design of head gasket, but I would include a copper fire ring milled into the head and block deck - such that when the head was clamped down, that copper wire crushed into a solid barrier that nothing could pass.

It works for race engines, why not for a production motor? Oh right, because they aren't "supposed" to ever "need" just such a high intensity type of seal.

My motto is "anything worth engineering is worth OVER engineering.

Mike92104 · **Posted:** Sun Sep 07, 2014 6:20 pm

I thought the head gasket had a viton coating. If so, hylomar or copper spray shouldn't be used.

flman · **Posted:** Sun Sep 07, 2014 7:01 pm

Mike92104 wrote:

I thought the head gasket had a viton coating. If so, hylomar or copper spray shouldn't be used.

That is true, that should pretty much fill in the tiny imperfections.

Mike92104 · **Posted:** Sun Sep 07, 2014 7:13 pm

how bad is the pitting? Does your fingernail catch on it? If it doesn't, I would just clean it up and install the gasket.

greiswig · **Posted:** Sun Sep 07, 2014 7:53 pm

Mike92104 wrote:

how bad is the pitting? Does your fingernail catch on it? If it doesn't, I would just clean it up and install the gasket.

The pitting shown in the picture definitely catches your nail. I don't have a good way to measure it, but it is more than a surface stain.

greiswig · **Posted:** Sun Sep 07, 2014 8:01 pm

flman wrote:

Mike92104 wrote:

I thought the head gasket had a viton coating. If so, hylomar or copper spray shouldn't be used.

That is true, that should pretty much fill in the tiny imperfections.

It's the not so tiny imperfections that worry me. Seems like the thinness of the viton coating basically relies on perfectly machined surfaces.

WolverineFW · **Posted:** Sun Sep 07, 2014 8:43 pm

Mine had similar imperfections showing after I cleaned the block up. After reading about the contruction of the metal head gaskets similar to ours I decided that it should be fine the way it is. I put the new gasket on, reinstalled the head and installed ARP head studs.

No issues so far. My coolant level has not moved at all in the bottle.

greiswig · **Posted:** Sun Sep 07, 2014 8:44 pm

WolverineFW wrote:

Mine had similar imperfections showing after I cleaned the block up. After reading about the contruction of the metal head gaskets similar to ours I decided that it should be fine the way it is. I put the new gasket on, reinstalled the head and installed ARP head studs.

No issues so far. My coolant level has not moved at all in the bottle.

That's encouraging.

geordi · **Posted:** Mon Sep 08, 2014 1:25 am

Bear in mind - That has been the result of EVERYONE that has replaced the factory bolts with much-more-precise ARP head studs.

The system is designed to seal properly when assembled and clamped properly - with 130 lb-ft of torque on the center bolts around the cylinders, you are creating something on the order of 19,000 PSI of clamping force. The factory bolts are slightly less than this when installed properly... And after innumerable heat cycles... Who knows how strong they still are.

ARP studs are awesomely engineered. I'd use them everywhere if I could afford them.

greiswig · **Posted:** Mon Sep 08, 2014 10:11 am

geordi wrote:

Bear in mind - That has been the result of EVERYONE that has replaced the factory bolts with much-more-precise ARP head studs.

Well, I know of one who it wasn't a silver bullet for, but I'd expect it not to be a silver bullet. He continues losing coolant and getting pressure in his cooling system after installing a new gasket and studs.

But I take your point.

greiswig · **Posted:** Mon Sep 08, 2014 4:11 pm

I'll talk to the shop that is checking out the head when I pick it up. If they ever get done with it! I'd like to get their take on the coating versus no-coating debate, and how they would deal with the corrosion...oh, and that one seal-related dent you can see in the second picture around what I think must be a high-pressure oil galley?

In other news, I unpacked the head gasket to see what it looked like. Stupid packaging...it left 1/4" diameter pieces of paper adhering to the surface of the gasket. Now I have to try to get that off without damaging the viton. Yay!

WWDiesel · **Posted:** Mon Sep 08, 2014 10:50 pm

Another option:
As an old mechanic, I have installed a many a head/gasket over the years with slight block imperfections using Permatex High-Tack gasket sealer sprayed on both the block, head and both sides of the gasket and have never had one leak using this product. It is a super product! :2cents:

If I were replacing my own CRD head gasket tomorrow, this is the only product I would consider using...

Check it out:
Permatex® High Tack™ Gasket Sealant
Fast-drying all-purpose sealant dries to a highly tacky, non-brittle film. A reliable general adhesive remains tacky indefinitely – can be applied in advance for convenience in assembly. Remains effective at temperatures of -65°F to 500°F (-54°C to 260°C). Sensor-safe. Resists gasoline, oil, antifreeze, axle lube, kerosene, propane and butane.

Please tell me I don't need to resurface the block

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