Best way to clean the block?

[JStoked]

So I'm replacing my hg and was wondering if it would be ok the use a bronze polishing wheel to clean the block off with? Going back with a stock hg only want 300 out of my every day. I know I should know this by now but just want to make sure. We put oil socked rags in the cylinders to catch all the crap that came off and when we were done used accitone to clean the top of the head on the block side.

 

[92ma71]

no use a flat jitterbug sander. no polishing wheel. if anything just use a piece of wood and some fine sandpaper to clean it, if your not getting it machined

 

[jetjock]

Roloc...

 

[Kai]

I used a twisted wire brush on an angle grinder. Cleaned it in minutes.

Then went over it with a sanding block & wd40 in several grades from 240 to 1200.

 

[IJ.]

I wonder why there are so many "My rebuilt 7M has a BHG" threads.... :nono:

 

[suprarx7nut]

I wonder why there are so many "My rebuilt 7M has a BHG" threads.... :nono:

No joke. Sandpaper, wire brush, what the hell? Your engine block is a precision built piece of machinery....

I... Why.... How would you think..... Ugh, nevermind.

Op: simply scrape off what you cam with a razor scraper and gasket remover. No sandpaper, no wire brush, nothing like that.


Sent from my ADR6400L using Tapatalk

 

[Kai]

Ehh....i'm using a stock gasket with ARP's. Used a straight edge & feelers to verify it wasn't warped, and made sure the oil pan and passageways were devoid of any 'crap' that may have fallen in. Note, i'm not endorsing that method, just explaining what *i* did. When i originally asked about how to clean the block surface, no one gave me a straight answer and it's a little late for me now, either it'll be fine, or it'll go boom. But for the benefit of others, enlighten us.

 

[suprarx7nut]

Stock headgasket and ARP should give you the best chance of success, but anything that *may* create any kind of shallow area or dip in the block surface is a huge nono. It can be tough to tell if you've created one unless you are very thorough with a straightedge and feelers. If you discover you've created a shallow area with the motor in car, you're pretty much fucked. Lapping the block can easily result in the same shallow areas, just on a larger scale. If you find shallow spots, time to pull it out and let a professional machine it perfectly flat. Then (and only then) can you use a MHG and get yourself even more security.

The OP doesn't sound like the head is going to be/has been machined. I will never understand why ANYONE would ever take a GTE head off for a new HG and not get it machined flat. $75 and 2 days of waiting. Who can't do that? Why wouldn't you? Getting the aluminum surface of the head clean AND keeping it flat is easily twice as hard as cleaning the cast iron block.

Anyways, I digress.

OP: Your answer is no, using a brass polishing wheel, wire wheel, sandpaper, lapping block...etc. is not a good idea. Use gasket remover and a razor blade scraper. If you want it cleaner, pull the motor and do a proper rebuild. And for the love of all things great in this world, please get the head machined flat and cleaned before putting it back on.

 

[Kai]

$75 for you, maybe. Here, it costs more like $350 and it's nearly a 2 hour round trip to drop it off, even if i trusted the guy. The head, i cleaned by hand, checked with the straight edge and feelers as per TSRM. It wasn't going to get machined either - insane cost of $200+, and the minimum they'd take off would be 20 thou, and i'd balk at having more than 2-5 thou being removed.

IMO, yes, if you're going for MHG, get it done properly. For stock though, it sounds a little TOO paranoid. There's nothing in my oil pan other than oil. The passageways were cleaned with bore brushes. The block surface was flat enough. This is how it looked:

When the gasket & head went on, the surfaces were CLEAN. Nothing but gasket between them. Now it's built & finished, it started fine, there's good compression in all cylinders, oil pressure is 40psi cold idle, 20psi hot idle. I did a drain of the oil pan on startup, then an initial fill of 10w40 , until warmed up, then it was swapped out for a fresh oil filter and another load of 10w40 which will be used for the next 100-200 miles before i drain that out, and fill with 5w30 and a new filter again. Coolant system was fully flushed as well, as a 'just in case' measure.

 

[Turbo Habanero]

40psi and 20psi oil levels hmmm.. mine is only about 35 and sometimes hot idle can be as low as 10-17 (stock gauge)

 

[Poodles]

Roloc...

This...

 

[Kai]

The stock gauge is crap - don't put too much stock in what it says. Measure with a proper gauge hooked up.

 

[JStoked]

Sry didn't make it clear the head that is going back on has been machined and cleaned.

 

[suprarx7nut]

$75 for you, maybe. Here, it costs more like $350 and it's nearly a 2 hour round trip to drop it off, even if i trusted the guy. The head, i cleaned by hand, checked with the straight edge and feelers as per TSRM. It wasn't going to get machined either - insane cost of $200+, and the minimum they'd take off would be 20 thou, and i'd balk at having more than 2-5 thou being removed.

IMO, yes, if you're going for MHG, get it done properly. For stock though, it sounds a little TOO paranoid. There's nothing in my oil pan other than oil. The passageways were cleaned with bore brushes. The block surface was flat enough. This is how it looked:

When the gasket & head went on, the surfaces were CLEAN. Nothing but gasket between them. Now it's built & finished, it started fine, there's good compression in all cylinders, oil pressure is 40psi cold idle, 20psi hot idle. I did a drain of the oil pan on startup, then an initial fill of 10w40 , until warmed up, then it was swapped out for a fresh oil filter and another load of 10w40 which will be used for the next 100-200 miles before i drain that out, and fill with 5w30 and a new filter again. Coolant system was fully flushed as well, as a 'just in case' measure.

Wow, thats a huge price difference. Why the huge gap? Anyways, for the OP, cost should be under $100 easy.

Kai, the problem isn't getting it clean, it's keeping it perfectly flat. You can get an absolute mirror finish cleaning and sanding by hand, but if it isnt perfectly flat, you may as well have left it dirty. It's not as if you'll have a BHG within a year just because you have a low spot (although you certainly could right on start up), but when the gasket gets a little old or the head gets a little too hot, it'll be under the gun and there's going to be less pressure holding the gasket in that one spot. That'll be the most likely failure point.

Good luck and I hope it holds for good. It's certainly possible its still flat, but its a gamble.

40psi and 20psi oil levels hmmm.. mine is only about 35 and sometimes hot idle can be as low as 10-17 (stock gauge)

With the stock gauge, you should figure a margin of error of ...maybe 35%. If your gague reads 40 psi, you might actually have 25 psi or 55 psi. Dont ever use the stock gauge as a numeric indicator of your engine's health. I swear, that gauge might as swell not even have numbers on the dial...

Sry didn't make it clear the head that is going back on has been machined and cleaned.

Good deal.

 

[Kai]

In the US, you can't go 20 miles without tripping over a machine shop. Here, the only ones i know of, are in Rennes (80 mile round trip) or Dinan (roughly the same distance). In both cases, they just charge a lot of money. They don't really cater for anything other than tractor engines, due to the fact that modifying your car is illegal here, in many ways (mine's not registered here, so i can get away with it). If a car blows its engine here - it's cheaper to replace the car, than bother repairing it.

Mine was definitely as straight as it was going to be. I'm not advocating this method to anyone, just simply detailing 'what i did'. In all cases, 'caveat utilitor' applies.

 

[grimreaper]

8 thousandths of warp-age was enough to leak coolant externally down the side of the block for me with a stock HG. To the naked eye, the surface looked perfect.

i messed with the remaining "high" spots since i knew at least 10 thou. had to come off the block.. with 800 grit I could remove a few thousandths in minutes creating even more dimples in the surface. It can get out of hand quick. Just clean the surface with acetone or some other solvent. or invest in a proper lapping plate or some sort of metal stock that can have a flat edge put on it. The hard thing is going to be keeping consistent pressure across the entire deck surface..

 

[IJ.]

Human physiology won't allow for a Flat true surface, even less so with a normal sized sanding block, my lapping plate is 12"x 12" and I only use it for finishing due to the above reason.