joestox

I've got a 1994 4Runner with a leaky head gasket. Its been a very small leak for a year and has recently started getting larger. I only get a little bit of white smoke out the exhaust from a cold start. Most of the leak seems to be coolant leaky to the outside on the drivers side. I am working up to tackling this project and my basic plan was to remove the heads and remachine them in the process. I was also planning on giving the valves some love as well. But I was not planning on taking the engine block out and remachining it as well. Is this going to work for me? I had a neighbor tell me it won't work unless I machine the block flat as well.

Any general advice here?

scope103

Does your neighbor know what he's talking about? Are you willing, instead, to rely on some stranger on the internet?

You only need to machine the block flat if ... it isn't flat. http://web.archive.org/web/201003261...ne/69cylin.pdf You need a straightedge to tell, and you don't have one. (Note that there is a "typo" in the manual cited; 0.05mm is 0.002in, not 0.0002in) You're looking for 0.002", and even a "pretty good" straight edge is only a little straighter than that anyway. , or you could borrow a "really good" straightedge (unlikely).

The good news is that in the absence of visible damage, you probably don't have to flatten your cast iron block. You might have to flatten your aluminum heads. There's no good home-shop way to machine the valve seats, so while the heads are at the machine shop you want them to check for flatness, and if out just a little, "kiss" the heads in the mill. Remember that every time you "flatten" either the head or the block, the pistons get closer to the valves. That will raise compression, and change timing (if you need to take off a lot, you can get over-thickness head gaskets to make up the difference. But if you are in the process of taking that much off, you might want to re-think restoring a 28-year old engine.)

joestox

I will invest in a rly good square. I like that idea best and I will get my tax return soon.
@scope103 How will I know what a lot to take off is? If the machine shop comes back to me and says they took of 5 thou for example is that in the ballpark of needing an extra thick gasket?

scope103

I don't know. These folks https://www.ebay.com/itm/390441129762 offer an "over-thickness" gasket that is 0.5mm thicker than stock.

Why a square instead of a straight-edge? Your carpenters framing square won't even be close. A precision square big enough to test the whole head surface might be a little expensive. https://www.penntoolco.com/starrett-...p-50142-20-36/

joestox

Ah sorry - I meant the straight edge. I will get the one you linked.

JJ'89

A quality automotive machine shop can advise you on this, after examining your heads. A major challenge in DIY engine work is finding a quality machinist.these days. They will know or have access to information for the surface finish requirements, etc. Do you have particular shop in mind?

joestox

@JJ'89 I just moved to Santa Fe. I do not have a particular shop in mind unfortunately - a quick google search shows at least 1 or 2 in town. Maybe it sounds like it would be better for me to go to Albuquerque or Denver to get the work done.

JJ'89

Not necessarily. True, there will be more shops. I think references from credible sources would be your best bet. How to find ? Maybe local car clubs, 4-wheelers clubs, even drag racers. Just cuz somebody's brother-in-law works there not particularly credible. It's not easy. Less easy nowadays I think cuz so much stuff is more reliable (like my '08 Corolla) and built to be reliable. that not as much demand for a automobile-oriented machine shop.

Your year model vehicle and type engine plugged into youtube videos, e.g. "89 Toyota 22RE valve job" for mine, will bring up an amazing amount of info. I get the sense that the V-6 engines in these vehicles are an expensive PITA. Try videos on "machining XXX block" or "recondition xxx cylinder head. Might not help you find a good shop, but could clue you to particular idiosyncrasies. Good luck on your repairs.

JJ'89

Not necessarily. True, there will be more shops. I think references from credible sources would be your best bet. How to find ? Maybe local car clubs, 4-wheelers clubs, even drag racers. Just cuz somebody's brother-in-law works there not particularly credible. It's not easy. Less easy nowadays I think cuz so much stuff is more reliable (like my '08 Corolla) and built to be reliable. that not as much demand for a automobile-oriented machine shop.

Your year model vehicle and type engine plugged into youtube videos, e.g. "89 Toyota 22RE valve job" for mine, will bring up an amazing amount of info. I get the sense that the V-6 engines in these vehicles are an expensive PITA. Try videos on "machining XXX block" or "recondition xxx cylinder head. Might not help you find a good shop, but could clue you to particular idiosyncrasies. Good luck on your repairs.
So it only took 0.003" cut to clean-up these heads. Trivial but the surface condition will influence the probability of a successful job. I don't know about Toyotas, but on your old cast-iron V-8s like my '65 Chev, if you take much off the head, the intake manifold needs to be cut too to fit with fastener holes lined up. A (quality) shop has all the reference data and skill and experience needed.

End of ramble...