83

I'll try this here...

I'm replacing my headgasket. I know I need to clean the threads out (maybe shop vac and q-tips?), but how important is chasing the threads? I see a lot about it when I search.

So, do I need to do it?

And if the answer is yes, can someone point me toward the tool and the right size for my 20R engine head bolts?

With all the talk of engine rebuilding and head gasket replacement advice I see given out, somebody must have experience with this.

snobdds

Yes, you need to really clean out the head bolt holes. Easiest way is to just take an old head bolt and cut a slit in the bottom with a die grinder and cutting wheel. Then deburr the bolt and run it in and out multiple times. Most of the stuff will get caught in the slit at the end of the bolt.

Then give it a good spray with break cleaner and hit it with some compressed air.

Repeat until no more stuff comes out. It is time consuming, but it will let the bolts get a good clamp on head and hopefully prevent future head gasket problems.

nothingbetter

Good idea with putting a cut in the old bolt. I've never thought of that. I like it. Cheap, simple effective. *thumbs up*

My logic says, your working on a old vehicle covered in rusty, metric hardware. Why not buy a tap and die set with the size you need for the head bolt. Sure it costs more than using a bolt, but I'm sure it will be continually useful as you keep wrenching.

83

Ok, thanks.

I don't have a grinder...But we'll see.

So I guess I should just call the Toyota parts department and get the size of the bolt, and the thread pattern from them? Hopefully they have that sort of thing.

Not sure yet if I'll replace the headbolts. If they aren't rust & corroded, I probably won't.

It's been a long time since I've been this far into an engine...If I can get the head off with the exhaust and intake manifolds still attached, what other (if any) gaskets am I going to need to do this job?

It's a pretty low mileage engine so unless I see something I don't like, the timing cover is staying on and I'm not touching the timing chain.

And I know how the exhaust bolts go anyways...they seem to just ask for an excuse to strip. So I'd like to leave them alone, even though a new exhaust manifold gasket would be nice. I don't think it's leaking, but you know.

CJM

Always replace the bolts.

83

I keep hearing different opinions on this...

I thought Ted from engine builder told me that, once. But then I was preaching that gospel, and the person I was trying to convince posted his discussion with Ted, and Ted told him he'd be fine using the old ones.

So...

CJM

You can use the old ones if you want, but its cheap insurance if you replace them.

83

Good point.

I guess I'll see what they cost and if a local place has some in stock. Not hard to run over to the dealership or parts store if I start pulling the old ones out and they don't look so good.

C17loadclear

I would not use a tap and die. Use a thread chaser. It will only clean the threads and not cut new ones. I put a little vaseline on it and it will get all the rust out.

83

Ok, so there's a tool called a "thread chaser", that I can buy in a store?

C17loadclear

Yes. I bought a kit at Sears that has several different sizes..I think it was like 45 bucks on sale.

83

Alright, thanks. Whatever words I was using to google it before wasn't really bringing up much, but thread chaser does.

Toyota says the head bolts are 12mm, 1.25" pitch (which he says the catalogue never usually tells him, so we got lucky), so I should be able to find what I need. They're also $6.50 a piece! $65 for the bolts...and only $15 for the head gasket! Oh well.

Thanks!

snobdds

Make sure if you use a thread chaser, it is a "bottoming" out type.


That is why an old head bolt is so useful, it is already a bottoming type and no need to get a special tool.

83

Gotcha, thanks.

I'll just need to decide if I'd rather buy a grinder or a chaser tool, then. Both would come in handy later...

83

Got the head bolt price down to $45 from Toyota, so that helps

83

I've got the head off.

There is carbon buildup on both the tops of the pistons, and the valves. Is there a reason to clean this off?

If it's a good idea to clean them off, what should I use? Brillo pad? Or something stiffer?

snobdds

I would clean it off. Carbon build up can cause your compression to increase and if it's bad enough...predetonation.

I use green scotch bright pads and lots of break cleaner...

83

Some old guy at the parts store said he never cleans his off anymore, since every time he did, he ended up having to replace the bearings...since that carbon turns into powder and gets everywhere.

BS?

I'm already worried about all the brake cleaner and stuff that's probably made its way into my oil. I plan to run the engine just enough to heat up and circulate once it's back together, change the oil, then probably change it again in a couple days.

But you would definitely recommend cleaning it?

Also...I know it's hard to say, but as far as I know this engine has never been overheated. I used a straigtedge and the head seems flat. Would you bring it to a machine shop anyway, just to make sure?

I had an external leak. Just a little stream of coolant running down the block on the exhuast side. Not sure if that's normal, or if it might mean a cracked head or something instead of headgasket?

I don't know.

ConSeann3ry

I reuse my bolts, just run them through a die. They have torqued down just fine. Oven cleaner works pretty well for getting that carbon off. I would be more afraid putting it back on with all that carbon on there...where is it going to go? Hopefully it stays, or burns off out of the exhaust, but if a chunk of it breaks off then it's in your chamber. I've checked it with a straightedge and it's been fine, most will tell you to have it decked. Kind of a better safe than sorry. Most gaskets will tell you they don't need to be re-torqued. If you do everything right they don't, but I would check it after it gets to running temp the first time just for the peace of mind. If you had some dirt on some of those threads they can be out of whack.

83

Hey thanks.

I used new bolts, and cleaned and chased the bolt holes in the head.

I had the head machined and cleaned.

Left the carbon...

I will retorque. Got it up to temp yesterday, and will change the coolant today. And oil. Wanted to let everything circulate, then change all the fluids again, since I sprayed a lot of brake cleaner around, and I'm sure other crap got into both the oil and coolant passages.