7M Head Condition Confusion

[CBatstone]

I am having a hard time determining if my 7M GTE Head is good…or not.

I had it sent out to Pittsburgh Crank for a rebuild, they cleaned it up, decked it, and mailed it back saying it was ok. My other shop who did the engine work, says it does not look good.

He says…“the cam journals are wavy and the cam and everything in the top side of the head is too scratched up”​

Then I’ve Read the following online…

"Also note that the bearing journals on the 7M cams are coated with a soft bearing
material that is easy to scratch and mark up. Most 7M's will have these
scratch marks when you pull the engine apart. What you may see are scratch
marks on the journal that look like a badly galled up bearing journal. This may
look bad but is normal and will not hurt anything. Do not attempt to clean the
surface of the cam journal. Just inspect it for bad cuts or grooves in the
journal that are into the cam material not just marks in the soft journal
coating material."​

And

"Camshafts from the 7M will oftentimes have a gouged appearance to them. They are fine, and you will be hard pressed to find a set that arent the same way anywhere else. The "gouging" or "scoring" is caused by aluminum buildup from the head. Dont polish them unless they are extremely rough. Polishing the aluminum off will only make your clearances larger in the head and contribute to oil pressure loss. The aluminum will only build up again over time."​

I don’t know what to do. The Head was a Fresh Rebuild 15k ago. I did run some material through my bottom end, but I’m not sure how much it affected the top end. Can anyone advise on this situation? I am trying to sort this out from several states away and it’s proving to be a very time-consuming task to keep sending it around.

Thanks in Advance for any help someone could offer

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If you want the history….

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My engine was built incorrectly by the previous builder, they probably didn’t set the thrust washer and 15k later my crankshaft had shifted the main caps and copper remnants were scoring my bearings and was likely the cause of a ring failure on cyl 5. Before tearing it apart, it took a breaker bar and way too much force to turn the engine over. It was described to me as an engine “brake” for lack of a better word.

So 1400$ later my bottom end short block assembly is ready to go. I just have been fighting to sort out my Head issues. I tried to buy one from Casey Radtke (back in November, 06’) who is building a 1 & 2 UZ-FE Twin turbo setup. He took my $175 and never sent me a head, or a refund.

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1990 7MGTE

 

[starscream5000]

Don't worry about the cams or cam journals, don't clean them up just like the quotes stated, that part of your head will be fine. I'm guessing the guy you took it to that said they didn't look good doesn't know much about a 7M head huh?

 

[CBatstone]

Don't worry about the cams or cam journals, don't clean them up just like the quotes stated, that part of your head will be fine. I'm guessing the guy you took it to that said they didn't look good doesn't know much about a 7M head huh?

He doesn't. He builds everything from Domestic V8's to the 12cyl Rolls Royce engines that the redbull aerobatics planes use. I think/hope he did a good job with my bottom end. But I don't think he knows too much about this 'weird' condition with the 7M Aluminum Heads.

Are there ANY other determining factors as to weather the head is bad or not?

- Craig

 

[starscream5000]

Did he check the structural integrity of the head? A brand new 7M head should 116mm tall from the cam deck to head deck, make sure there hasn't been too much material removed. How do the water jackets look? Corroded? clean them up if so. Look for any visual stress on the head. I suggest getting a 7/16 helicoil kit from driftmotion for the exhaust studs since you have the head out and those things love to NOT hold torque, or strip out before you reach the required spec for them. Don't forget to shim the valves when reinstalling everything.

 

[CBatstone]

I just talked to the machinist again. While he isn't a specialist this is what he said. Unfortunately I can't get pictures yet, but maybe next week.

He said that the journals look tore up and there are big gouges where the caps bolt down onto the cams. He says it looks like a loss of material, like metal has been wearing at it and it could cause the cams to be loose. He wouldn't put this on a customer motor, and would be suprised if I wanted to run it on my new motor. Then I read these articles and it almost looks expected?

how much is too much? Are we talking about the same things here?

 

[3p141592654]

The only thing that should look bad is the cam journals (on the camshaft). The cam bearings in the head should look smooth as glass.

We need pictures to make a better call.

Take a look at the pictures in this thread. Print them out and go compare with what you have at the shop.

http://www.supramania.com/forums/showthread.php?t=16390

 

[Poodles]

it's normal for that to happen when you have metal get thrown through the engine (I spun a rod bearing)

machine shop was able to clean everything up though..

 

[GrimJack]

The are other things you need to check.

You need to have the head checked for hardness. If it's been overheated a bunch, the aluminum will soften. The check is easy to do from what I understand, and should be free or next to it.

Also, you need to have the cam saddles checked for straightness. If your head was warped, and the machine shop just cut the deck to make it flat, then your cam saddles will still be warped, and running cams in it warped will destroy them.

 

[CBatstone]

Fortunately the engine never overheated. We found the problem when we pulled the head to install studs and a new head gasket as preventative maintenance.

I sent the head to a machine shop expecting them to rebuilt it and they crack/pressure tested it and cleaned it and sent it back to me. So I was a bit confused about its condition when another shop said it looked bad. But thats easy to understand when its widely accepted that the 7M head appears to be a big f-up by Toyota. An engine head should be a smooth operating piece of engineering. It was unfortunately designed to eat away aluminum and have it collect in the head and score up the precision machined surfaces.

Who knew that some simple upgrades would turn into a complete rebuild. If this engine doesn't run reliably for me for years, supra and I are going to have some deeper issues in our relationship.

I really just want to drive my car.

 

[3p141592654]

There is nothing majorly wrong with the 7M head. The cam journals have a soft babbit coating that is soft (and has a strong sulfur smell). It is not aluminum scraped from the engine, not sure where you got that idea.

The cam journals should wear smoothly. If the bearings are out of spec, just lap the caps to get them back. All the wear is in the caps because the loading is all from the valves pushing upwards.

If the bearings are chewed up because you had crap in the oil, then that is certainly not a design fault.

 

[CBatstone]

There is nothing majorly wrong with the 7M head. The cam journals have a soft babbit coating that is soft (and has a strong sulfur smell). It is not aluminum scraped from the engine, not sure where you got that idea.

If the bearings are chewed up because you had crap in the oil, then that is certainly not a design fault.

"The "gouging" or "scoring" is caused by aluminum buildup from the head"

The cams ride right on the aluminum, I haven't heard of bearings in the head, though it seems like it would be a good idea to have inserts like on the crankshaft.

 

[CBatstone]

Response from my shop - Keep in mind I am many states away and cannot asses them myself.

"We looked at the head when we where taking the
pictures. Our opinion is that the head is fine. The cams are the
things I am worried about because of all the groves in them."

 

[CBatstone]

more pics

 

[starscream5000]

The head looks fine, the cams are what I expected. Did they clean the cam journals?

 

[3p141592654]

Agreed, the head looks fine. The journals look typical. The grooves should be in the soft babbitt stuff only. I can't tell from the photos if they extend into the steel, which would be a problem. Since you can't inspect them yourself, I would suggest that they polish the journals and then the scratches should disappear, along with the babbitt. Make sure they plastigage the bearings before putting it back together. Lap the caps if the clearance is excessive.

 

[IJ.]

LOL and if you were being really anal about it you'd linish the Cams then align bore and hone the Cam tunnels

 

[CBatstone]

The second photo in from the left (of the cam) is the spot which worries us. The gouge is into the metal. I know the head itself is in great shape. It checked out OK, and it was never overheated. But the cams are the problem area. It's going on a short block which I've put a lot of money and time into. Should I spend 450$ and buy a freshly rebuilt head&cams, or should I use these, or attempt to locate another cam which might not be so bad. Which could be hard to do from what some users say. They've ended up with worse than they started with.

 

[starscream5000]

Get it polished first, then go from there. If you decide you don't want to use it, keep it anyways in case the others aren't in as good of shape as this one is.

 

[Poodles]

I had mine polished (rod knock engine with metal in the oil, cams looked BAD), they came out great...