bsanders30096

95 4Runner SR5 185k. I just got my heads back from the machine shop. The surface finish on the face that bolts to the block seems to be a bit rough. The grain runs the length of the heads, not in a circluar motion? Does this seem odd? I can feel the tiny grain marks with my finger nail...ever so slightly, but still I can feel them. I want to call my machine shop, but I need to know for myself what the spec of the surface finish should be before I ask what they did. The surface finish for the exhaust manifolds is finer than the head surface. Please help. Thanks, Brian

wrenchmonster

Do you have any pictures?

bsanders30096

here's a picture...

wrenchmonster

Well, the roughness issue could be a problem, but you're not talking about bearings here either. I wouldn't be worried about what machine they ran it on (circular pattern or straight lines) but it looks like the speed at which they ran it was maybe a little fast. I'd deburr the edges on everything personally.

I might politely ask if they can clean it up for you. But, flat is flat. Run a straight edge down and check to spec. If that's okay, I'd slam it and jam it.

kyle_22r

take that to a reputable machine shop and have it redone. that is an absolutely piss-poor job of a resurface. probably one of those sleazebag shops that sticks cylinder heads on a large belt sander. i can almost guarantee a quick head gasket failure.

the surface of a head should be an almost mirror finish.

bsanders30096

OK, now I'm really confused. I called the machine shop and he told me that it's within spec. Supposedly some come out mirror-like, and some don't??? I'm not sure what to believe now. Can anyone else voice their opinion? I'll probably take it somewhere this evening for another opinion as well.

wrenchmonster

I understand what Kyle22r is saying, it is pretty poor quality vs. what you could get out there. However, I don't think it would fail as long as it's flat. The roughness, as long as it's not too rough, would be taken up in the composition of the gasket. I'd suspect the reason it didn't come out like a mirror finish was because the feed rate at which the machine was run at was too high.

Is it flat and will it work? I'd say yes. Is it ideal? Clearly not. If you are unsatisfied then you can either take it somewhere else or have the original guy do it again. If the original guy refuses, then I'd ask what kind of warranty he has on his work. And make him put that warranty in writing.

bsanders30096

After doing some research, I've learned that the surface finish should be 20-50RA (roughness average) especially for bi-metal configs. The finish can't be too rough (as in my case), otherwise it will embed into the gasket and will not allow enough play for expansion/contraction. Since the heads are aluminum, and the block is cast iron, the finish is critical on this setup. The finish cannot be too smooth either since it has to 'grip' somewhat. I'm taking it to another 'more reputable' shop to have it re-surfaced once again. Does anyone know the maximum amount of material that can be 'shaved' off the head and still be within specs? Thanks,Brian

wrenchmonster

Go talk to engbldr. He's going to know more about the subject than anyone else on YT. Get his opinion. In any case, good luck and I hope things turn out well.

mt_goat

Yeah e-mail that pic to EB. http://www.engnbldr.com/ That looks really rough to me too.

engnbldr

>>>*...Well.

I sent you a personal email....*EB

Chuki

Here's what your surfacing should look like... I'm not a machinist but that litterally looks like Kyle said, like someone used a frigging belt sander. I don't know if it'd work or not. Who Knows?!



This is what my heads looked like after being surfaced and hot tanked.

The finish should be a very smooth satin type finish.