.002" gauge test fails barely between cylinders

I just did a thorough clean of both my cylinder head mating surfaces with a razor blade, WD-40 and then Brakeleen and then performed a feeler gauge test using .002" gauge, which I understand is the threshold according to Toyota.

The test passes everywhere except on the left (driver) side in both narrow passages between the cylinders but fails barely cause I have to drive the gauge pretty hard, borderline force it to pass under the straightedge, when the straightedge is set lengthwise (along the long side of the head) in the middle. See below:



When it's set widthwise, it does not fail. See below:



The right (passenger) side head is fine, the .002" gauge doesn't slide under even when I push it hard.

Is this something I should worry about, i.e. have the left head ironed out by a machinist?

 

What are you using for a straight edge?

If you have to force it under, it's within spec. A feeler gauge should be relatively easy to slide for a proper measurement.

 

Is .002" the proper threshold?

 

yes, anything over .002" should be machined. They are right, if you have to force it, it's over. Should go under and move with little to no drag.

 

According to the factory manual, you have .0039 to play with. If you're having a hard time getting a .002 in there, you're fine.

Run it!

 

Dude, no way .0039 can go under.

 

There is a little more warpage on the block mating surface. I can force a .0025" under in the same places. Is the threshold the same on both sides?

 

Yes you should have the head machined flat. That is a potential blown head gasket in the making. I think that the drivers side is the one that is most prone to blowing a head gasket from what I remember...

 

I appreciate the concern, however, it's well within the spec.

 

I was just going by your post where you said it failed. I didn't look up the specifications:

Where you said: " performed a feeler gauge test using .002" gauge, which I understand is the threshold according to Toyota.

The test passes everywhere except on the left (driver) side in both narrow passages between the cylinders but fails barely cause I have to drive the gauge pretty hard, borderline force it to pass under the straightedge."


If it is well within specifications why are you even asking about it?

Is 0.002 the threshold or not? If it is I would get it machined, If it is not I would not worry about it.

Color me confused. :\

 

I was asking to verify that my test that I was passing was indeed right and about gauge sizes.

 

Which @1MK answered

 

I do see by 1MK's post that the cylinder head is allowed 0.0039 inch on the cylinder head. and 0.0020 inch on the engine block.

So no, 0.0020 inch is not the correct threshold for the cylinder head, 0.0039 inch is correct for the head.

The cylinder block head face should be checked using the 0.0020 inch gauge.

 

But that isn't what you asked in the original post.

Whatever... My head is blowing up.

 

As others said, you should never have to force in the gauge. I bet the block's deck is closer to .0020" without forcing it.

Put it back together.

 

So I'm well within the spec on the head side and a little warped on the block side (.0025" but not .003") on the driver side. The other side all good.

 

Yes. If you can get a 0.0025 under the straight edge on the block head mating surface it is too much. Your head surface seems to be well within specification at 0.0020.

My thought is that if the block is out of specification at 0.0025 and the head reads 0.0020 at the same area the total flatness is off by 0.0045. As in a build up of tolerances that were maybe not considered. And could be a contributing cause of the blown head gasket on the drivers side head. 4.5 thousandths of an inch is quite a gap in a head mating surface.

 

The unfortunate part of all this is that IAW the service manual there isn't an option to machine either the head or the block. Both state to replace if they are out of specifications. You may be able to get by with a good head gasket sealant such as coppercoat or something like it.

http://www.speedwaymotors.com/Tech/engine-head-gasket-design-and-installation-tips.html

Head Gasket Coatings
There are mixed feelings on whether or not you should apply a sealer or coating to head gaskets before installing them. Some guys like to apply a "copper coat", such as KW Copper Coat or Permatex Copper Spray-A-Gasket. Years ago, some would even spray paint their gaskets before installing them. The idea is that it should help seal up small imperfections in the deck or head surfaces. Success can be achieved with and without copper spray - the individual manufacturer will usually specify whether or not you should use sealer with their gaskets.

But as always a good man has got to know his limitations.