DIY Engine Deck Re-Finishing

[Mike1992]

A few days ago I pulled my head to upgrade my head gasket and bolts as I'm wanting to go with a MLS and ARP's. The head is going to the machine shop and I'm working on making the engine deck as smooth as possible with a DIY in mind. I started off with a green scotch brite and some brake cleaner, then used some "goof off" chemical with another scotch brite. This got most of the junk off and I then began to block sand the deck surface with 400grit. After a few hours of 400 I moved up to 600grit and this is where I am now. There's some fairly deep pitting from the old stock gasket as you can see and I just can't seem to get it. Will a MLS gasket seal over the pitting? I plan to keep stepping up the grit paper I'm using for a glass like finish. Everything checks out with a straight edge and feeler gauges so far, so I know I'm not doing a horrible job. Thanks Mike

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[xlMcMlx DsM]

Get that thing glass smooth like you said. An MLS HG needs an extremely smooth(glasslike) surface to seal on. The surface finish of the deck and head are measured in Ra(roughness average) count. A machine shop should be able to measure it for you.

 

[BoredDSM]

STOP WHAT YOU ARE DOING! Doing such hand sanding would ruin the sealing surface of your block completely.

YouTube - Nissan SR20-DET Block Resurfacing

You are basically making the sealing surface between the head and block uneven and just asking for head gasket failure.

 

[Mike1992]

Video speaks alot I'm sure my block isn't 100% smooth across, but I did straight edge in various ways and the biggest feeler gauge I can get anywhere is 0.002" which is half of spec limit, so I'm sure I'm still good.

 

[BoredDSM]

In my honest opinion I think you should have it checked out. DIY resurfacing with sand paper and scotch bright pads is highly not recomended.

 

[mach4g63t]

DSMs, to me, are all about the DIY kind of things. I know for me, and probably a lot of people, it's what got them started in mechanics, building engines, fabrication, etc. If you're already started, what else can you hurt?

Like someone said, if you feel comfortable with how you've done, try it, or maybe finish it up and take it to a machine shop and have them check the surface to see how well you did.

Would I do this? Definitely not. Not worth the time or effort vice spending like 50 bucks to have a machine shop deck it for you. But more power to you!

 

[need2boostpsi]

hey man, im about 90 miles south from you! anyways when i put my AMS head on i used a new flat edge razor and gently scraped the old gasket off then used parts cleaner to shine my deck up, so far its worked out great although i did loose about 8psi of compression across the board with my OEM raliart 4-layer HG.

 

[SlowSpyder]

My question is how are you preventing any of the shavings from falling into the coolant passages and the oil passages especially the oil feed.

 

[No_Skillz]

Your MLS will not seal over that. You do have some hope if you decide to stick to OEM composite.

 

[KYNgsx]

I like how someone always posts something with a SR20 aluminum block any time someone asks this kind of question. My felpro seals fine with a hand finish, but I probably wouldn't do that if I was going with a MLS.

 

[Mike1992]

Well I seem to be getting alot of negative comments on my work so I guess I'll try and clear things up.

Yes the block is cast iron not aluminum and yes you can royally screw the deck surface up if not careful. This is why I lightly block sanded (across the entire deck surface) with 400/600 grit and nothing heavier. I've triple checked myself with a straight edge and feeler gauges and I am within spec ( 0.002") As for some fine dust/grit getting into the motor, yes that is another possibility. I've cleaned all the holes up with a rag and blown everything out with compressed air. There's wasn't any visable dust from this sand job either. I expect it to be cleaned away with some idle time in the driveway and an oil change no problem.

Nearly everyone on dsmlink forums seems to think things are going to work out just fine as I anticipated. It'll be a few weeks before she's back togeather, but, I'll post my final results when she's running again.

 

[jking29]

The smaller the number of the RA, the smoother it is.

 

[SonySlave]

I think that you will be fine with the deck surface you have. I did mine that way when I burned a valve a couple years ago. Granted, I used an OEM composite gasket because I couldn't take the risk of it not working because it was my daily driver and I never had a single issue. My friend burned a valve also on his 120k mile, FP3052 powered GVR4 and did the exact thing you did and used a Mitsu MLS and hasn't had a single issue running 32psi over the last 2 years.

So, say you spend $80 on a Mitsu MLS and it doesn't seal right. Not a total catastrophe. Worst case scenario is you have to redo the labor to pull the head back off, spend $40 more dollars and put an OEM composite gasket on it. With the deck surface you have now, an OEM composite will seal no problem, but you are taking a risk with the MLS. You already know that and I say try it anyway.

BTW, I tend to get better tech info from the Link boards anyway...

 

[jrohner]

From what I've seen around here, composite head gaskets are not problematic.

 

[blcknspo0ln]

The smaller the number of the RA, the smoother it is.

hah! then my whole line of thinking is backwards damn these quick google searches.

 

[96_charcoal_tsi]

I have done my head and block surface this way and have had no problems. I am using a cometic head gasket and this is the only way i could get it to seal up. Lets just say i will never use one of those gaskets again. Doing a headgasket twice for a stupid mistake is more than enough. But you should be able to get away with it as mine wasn't as shiny as yours and mine still sealed up. Maybe i just got lucky

 

[tkelly27]

You are measuring the flatness of the deck with the feeler gauge and straight edge. While you may have that within specifications, the MLS requires that the roughness (which is completely different) be within the proper tolerances to seal. It's the nature of the beast. It is unlikely that you have the tools to measure the roughness. I'm pretty sure at that fine the tool to measure it becomes like a stylus on a record player that "listens" to the tiny imperfections in the metal.

Roughness - Wikipedia, the free encyclopedia

Odds are, you'll be fine. So many people run MLSs with lift and slip without problems. If your fancy pants head gasket does happen to blow, you'll know who to blame though : )