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Hi there,

  I'm getting ready to assemble the engine in the soob after taking it apart to replace a bad head gasket. Is it a thing on Subarus to run a tap down bolt holes, and the bolts through a die to clean them up? And, I was taught to wash parts with a solvent first, then wash/rinse with a water based degreaser. What do you do? Of course I'll coat all the parts with oil as I reassemble. And I understand it's really important to keep the mating surfaces on the chain cover really clean to get a good seal. Is it really clean, like wiped down with alcohol clean? Or degreaser, like brakleen, clean? 

 

Mike

2001 Outback, LL Bean H6

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I wash down with petrol or whatever I have on hand. Then use metho to wipe all mating surfaces before applying silicone sealant (where needed) or fitting the rubber seals or the gasket needed. 

As for head bolt thread tap, I used GD’s suggestion of cutting a slice in a used headbolt (recommended to use new bolts if you don’t know their history or they’ve been used more than once - from what I’ve been told - and I’ve done this on my current HG job) and using the headbolt to clean up the threads. 

The rest of the engine cleaning, it comes down to how fastidious you want to be about it. 

Cheers 

Bennie

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I play it by ear. If I can't spin bolts in by hand, I generally run a tap in the hole and hit the bolt on a wire wheel. If it's greasy, I clean it. Engine internal parts shouldn't have any issue with either of those, but sometimes...

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2 hours ago, el_freddo said:

I wash down with petrol or whatever I have on hand. Then use metho to wipe all mating surfaces before applying silicone sealant (where needed) or fitting the rubber seals or the gasket needed. 

As for head bolt thread tap, I used GD’s suggestion of cutting a slice in a used headbolt (recommended to use new bolts if you don’t know their history or they’ve been used more than once - from what I’ve been told - and I’ve done this on my current HG job) and using the headbolt to clean up the threads. 

The rest of the engine cleaning, it comes down to how fastidious you want to be about it. 

Cheers 

Bennie

Thanks. I'm not familiar with metho, but I can GTS, and find out about it! OK, denatured alcohol. Correct?

Mike

Edited by Phermenter

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If you're going to use a tap to chase the threads, be sure it is a thread-restoring/thread-cleaning tap, NOT a thread-cutting tap.

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5 hours ago, Phermenter said:

Thanks. I'm not familiar with metho, but I can GTS, and find out about it! OK, denatured alcohol. Correct?

Mike

Yeah sorry, metho = methalyated spirits. It’s a white alcohol, not for drinking! 

I’m not sure what it’s called over your way (if it is named differently). 

Cheers 

Bennie

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Probably same as MEK around here, great for cutting oil/grease, that stuff will melt rubber and some plastics.  It leaves a residue so go over everything with brake cleaner just before putting on rtv.

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Petrol does fine for preliminary part cleaning, use gloves; it carcinogenic.

Water with degreaser is also effective.

Good old elbow grease with a stiff brush for crusty externals.

I also use denatured alcohol for ‘thoroughly de-greasing mating surfaces before assembly’.

Female threads are cleaned well, as already mentioned, by using an old undamaged bolt with a tidy saw-cut across the end threads and some deburring. This scoops out the oily grime from engine blocks effectively. Repeat as necessary and clean with paper or cloth and some air. I have also used a sliced nut in a socket to clean and hone bolt threads successfully.

I would not use a cutting tap unless the thread was deformed or damaged.

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I use brake cleaner for most of my cleaning.  The bolt with threads cut works well on female threaded holes.

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