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Author: Subject: Cylinder head water passage corrosion?
luke2152

posted on 25/6/19 at 09:13 PM Reply With Quote
Cylinder head water passage corrosion?

I'm building a toyota 3sgte engine out of parts sourced from a few engines. Started cleaning my cylinder head up and noticed that there seems to be bits of material missing around the coolant passages. If it was a cast iron head I'd call it corrosion but as its ally I think it might just be poor casting. It doesn't reach the actual cylinder seal on the head gasket although its pretty close. For the record I have another 3sge head (very similar non turbo one) and it has far less material missing. Not a straight swap though with a few parts switched.

So 3 options really-
1. Leave it be because it's just a casting flaw in a non critical place. Will be getting a skim anyway.
2. Option 1 but grind the sharp edges out to stop it being a place cracks could form.
3. Find another head or make the non turbo one work cos this one is F****d.

Image attached. What do you reckon?

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r1_pete

posted on 25/6/19 at 09:23 PM Reply With Quote
Looking at the corrosion its very close to the fire seal, Iíd say its verging on scrap, I wouldnít trust it long term.

Take it to a machine shop it may be salvageable by skimming, but itíll be close on making the cr too high before clearing the corrosion.

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ian locostzx9rc2

posted on 25/6/19 at 09:25 PM Reply With Quote
Agree with the last comment really doesnít look good
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perksy

posted on 25/6/19 at 09:52 PM Reply With Quote
That looks like its either been run with no antifreeze (or poor quality antifreeze) or stored without any in it

I had a C20XE Coscast cylinderhead and had some waterways welded and skimmed and it turned out very nice (Motorcast, Shropshire)

It wasn't as bad as that though

There's other damage to your head aswell
(Especially on two of the cylinders)



[Edited on 25/6/19 by perksy]

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rusty nuts

posted on 26/6/19 at 06:45 AM Reply With Quote
Definitely erosion caused by lack of decent antifreeze , itís fairly common for ally heads to be welded up in cases like that but get it checked for further damage before spending too much on it
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nick205

posted on 26/6/19 at 09:42 AM Reply With Quote
It doesn't look great and I'd not be confident rebuilding an engine with it.

Can the surface be skimmed and a thicker head gasket fitted to maintain the compression ratio?

Can a different (better condition) head be bought?

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motorcycle_mayhem

posted on 26/6/19 at 06:27 PM Reply With Quote
Can only imagine what the rest of that engine was like, coolant corrosion inhibitors clearly have not been used.
I wouldn't use it. It's worth it's weight (ca. £400 / Ton).

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SPYDER

posted on 26/6/19 at 07:42 PM Reply With Quote
If possible I would be using a REV3 NA head together with its cams. They have superior timing and are "shim under bucket" design.
Combustion chambers are 49cc.
Earlier manifolds won't fit though. You would need REV3 items.
Out of interest are you running it RWD? What gearbox are you using?
I have a 6 speed AZ6 from an IS200 on my car.

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luke2152

posted on 26/6/19 at 08:08 PM Reply With Quote
Had it to the machine shop today and they reckon they can weld and regrind and make it good as new for £100ish so I'm happy with that. Seats are in good shape too.

So I'm using Gen 2 NA block with Gen 2 turbo head but higher lift Gen 3 NA cams and underbucket shims. Topfeed fuel rail from Gen 2 NA with decapped rx8 injectors. Forged pistons and rods and a good sized chinese turbo (kinugawa knockoff of garrett gtx3067). And decent dose of W/M injection to keep the knock at bay. Its not going in the 7 but the MR2 it's made for - the goal being somewhere round 400bhp without spending megabucks.

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Mr Whippy

posted on 27/6/19 at 05:50 AM Reply With Quote
that's a good price
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