Are these 3.4L heads fixable?

Hi, I recently bought a 2001 996 C4 Coupe that came with a core engine. I’m fairly certain the heads aren't fixable, but I’d like to get some opinions before I start looking for a replacement set. Rough to the fingernail. My assumption is that if the scoring is cleaned up, I’d likely need oversized cam journals/cams or some type of line-bore repair, but I’m not sure what the realistic options are. I don’t see any obvious valve damage. Also worth noting: the heads are missing the cams and Variocam tensioners. Thanks! This is one of the covers.

Fixable. I've had the scratches (much worse than yours) on one cam bearing laser welded and then line bored. Cam cover needs nothing as that area only seats the plug. It will still seal. Do you have all cam bearing caps with the same number needle stamped on each head? 2 caps per head required. Since cams and actuators are missing, buying heads that need nothing or less, might be a more cost effective option. Clean out inside of cams once you have them. Where are you located? If Europe, then consider these https://www.kleinanzeigen.de/s-anzeige/nockenwellen-porsche-996/3421205008-223-1413?

Fixable.

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That looks like an amazing deal, but I'm in Phoenix, AZ, in the United States. I'm realizing I'm probably missing more than just the cams/tensioners. I have 1 of the covers and was going to get another if I went the fix-it route, but the heads have basically been stripped, except for the valves. Looks like I'm likely on the market for some heads if anyone has some they want to part with.

If rebuilding the heads, have the valve seats upgraded. The original ones tend to dislodge into the cylinders.

According to Hoffmann heads that is more an issue with 3.6l M96 heads than 3.4l ones. https://hamheads.com/2016/12/01/m96-...-general-info/

Len Hoffman (Hamheads) is the guy you should be talking to.

As long as we're talking about Len Hoffman's head work, agree his shop is where any set of 3.4 heads already off the engine and in more or less unknown condition should go. The main problem with 3.4 heads is head cracking causing oil in coolant to some degree, some more some less... This problem has been determined by the best m96 builders to come from old failed water pumps shedding broken impeller blades into the small thin coolant passageways blocking off areas from cooling that eventually crack with a fine hairline crack many times in the same few spots. It takes a high pressure(100psi_iirr) test to find these cracks and a jig set up for this specific job is needed. Len has/made these jigs Also a jig for flushing head of impeller blade pieces is also needed to do a proper flush of all impeller blades lodged in small head coolant passage ways. Len has/made these jigs. IIRR, Jake has stated before on our forums that about 9 months after a water pump failure/replacement many/most m96 3.4 have head crack problems /intermix. I would like to hear how "9 months" head crack/pump failure was determined. Because iirr Jake was very specific on 9 months. Don't get me wrong, I do believe Jake 100% about the relationship of failed WP and head cracks/intermix, just wondering how that exact 9mo timeline was figured... So, bottom line, those cam saddles being scored a little is really not a bad problem.cleaning them up just a little and engine can run fine. From what I can see in your pics. Of course a oil clearance would need to be measured to verify how those pics look. To me, whats drastically more important is to determine if the head structure is sound without cracks before any mony is spent on these heads. Or for that matter on any used unknown 3.4 heads, let alone a set of heads from a core engine...

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My guess is he tested it to see when it blows. I still remember when he and Charles were at a PCA track weekend at Road America well over 15 years ago trying to get everybody to drive a Boxster they had built to blow up an engine they were testing.

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Long, long ago: And we did blow it up eventually after years of abusing it on track. The crankshaft gave up the ghost:

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The good old days, before all the nanny cars!

I love those pictures and the story! An update: I went and had the heads looked at today, and he laughed at the scuffs, saying they are barely anything and can be lightly polished off, and clearances should still be good. The heads don't look overheated, and are in really good condition, aside from the scuffs. He's going to do a pressure test and clean them up, but since it doesn't look like the motor failure was head-related, I'm assuming the Hoffman pressure test likely isn't needed, as they appear to have been in running order when the engine failed. BUT I only posted 1 cover because it had only 1 cover, which I am not sure even went with this motor. I appear to be missing the following: 1 cover - are these bank-specific? I know they are supposed to be matched; we can chat about that below. 4 camshafts - I actually just purchased these, so hopefully these are fine - https://www.ebay.com/itm/117251427986 4 cam caps total - there doesn't appear to be any in the parts I have 2 variocam tensioners 2 variocam solenoids, unless they are considered part of the tensioners, when I buy them 24 lifters, I scoured high and low, and I do not have these 2 camshaft actuator gears 2 covers over the camshaft actuator gears Bolts, missing so many bolts. I have the bolts that bolt the heads to the block, but no other bolts. Anything else I'm missing? So, let's talk about the matching number covers to cylinder heads. My understanding is that yes, you want to keep them the same. BUT, if that's not possible, then the cylinder head expert I dropped them off with can make sure they are usable if I provide caps and covers that are close enough. He will make sure all oil clearances are correct and that they rotate freely. That brings me to sourcing the remaining parts. When I made the purchase, he also threw in a 2.7L Boxster motor that has a hole in one of the pistons. I haven't dug in deeper. Of the parts I need above, could any of them from those heads be used? If not, I'll be looking for some cracked heads or something so that I can source the parts without buying them individually. Any thoughts would be appreciated, as would an updated parts list if I missed anything. Thanks, Taylor

Get INA 420004910 for lifters. You can use the boxster head for parts you're missing. If you're lucky, clearance are ok off the bat or Hoffmann can machine them for the spec'ed clearance. Hoffmann's site lists the differences between the M96 heads and I'm pretty sure you can use much if not everything you require.

Here is a picture of the 2.7L heads in case that matters I think this is a replacement motor. I'm not sure if it's a 3 or 5-chain motor; I'm not sure if it matters. Cover is different than my cover on the 3.4 heads Engine Number

if I am seeing it correctly, there is a AT in that and serial number that means it was a factory replacement service engine.

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Yep, I think that's why I am having trouble identifying. This is the 2.7L, not the 3.4L engine number to clarify.

M96/23 is a 3-chain. Heads (with variocam+) not compatible to 5-chain (variocam) Its 2.7l crank has the same 78mm stroke your 3.4l has. If your 3.4 already has the toothed/hyvo chain to drive the IMS, then the 2.7l crank is a direct fit replacement. If your 3.4l has roller chain then you'd have to carry over the IMS too and unfortunately loose the double row IMS bearing.

If it�s a newer AT motor it might have the big/non-servicable IMS anyhow? Obviously since they are building it they can put a replacement big bearing in.

I'm a little confused. Are you guys talking about me taking insides from 2.7L 3 chain heads for my 3.4L heads, and the crank and IMS shaft and converting to a 3 chain motor?

If you don�t mind,,I would like some more info�.when you say. �came with a core engine� does that mean the car you bought didn�t have an engine in it? That 2.7 engine is not compatible with that car,

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The car came with two engines, neither of which were original to the car. The car had been supposedly abandoned at a shop after engine and tranny failure. It did, however, come with a core 3.4L M96.04 5 chain motor. Separately, he tossed in a 2.7L engine. So far, I looked at one piston on the 2.7, and it had a hole in it. I didn't dig any further into that motor until today. The hope was that this was a 5 chain 2.7L, so I could steal the parts for my 3.4 heads.

Thanks for the clarification,have a successful journey.

So you bought a roller 996.1 and a partial core 3.4 5 chain and a full core 2.7 3 chain in hopes of mixing and matching enough good parts to get it going ? Very ambitious for someone with limited knowledge on the M96/7 engines ... What people are telling you is that the only thing from the 2.7 that can be used on the 3.4 is the crankshaft and IMS ( intermediate shaft ).. nothing else will be of any use on the 3.4 engine so you will need to source the missing parts..

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What's life without an impulsive project-car purchase here and there... The 2.7 was just a toss-in that he had the 3.4 next to it, and he didn't really know anything about them, so it was a bit of a blind leading the blind moment. It sounds like my 2.7L is pretty much a paperweight since my crank is fine in the 3.4 and I can't steal the other parts. Back to the original parts list since I've got the wrong spare motor... Do the head parts (from the list above) from 2.5, 2.7, and 3.4 all work as long as they are 5-chain motors? 2.5L heads are a dime a dozen and seem quite inexpensive. Can I steal parts off of those to finish out what I'm missing for the 3.4L? Thanks, Taylor

The vario-cam actuators and cam gears are the same on all 5 chain engines, but only the 3.2 and 3.4 have the bigger cams and larger valves...

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I have valves and bought cams. Do you know if lifters are also the same?

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that 3.4 crankshaft has value, if it is good .don�t dismiss what you have.

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Lifters are the same but you should really get new ones unless your dead set on using the lifter cradle �nd lifters from the donor M96/23 2.7l (mark where they were installed before removal and put them back in the same spot in the head you fit the cradles to).

Just going to leave an update. I acquired a 5-chain 2.5L engine for $250, and the heads looked to be in great shape. I also picked up a set of cams off of eBay for a 996. I swapped the internals over to my 3.4L and got all the missing bolts from the heads for the cradles and covers. The cylinder head shop did the slightest bit of massaging of the caps, but everything looks to be in good order. He's going to check the lifters and perform a valve job.

That is interesting. If you don't mind, can you say how much you paid for the project car with the engine? I am always curious if it is worth buying project car vs cheaper working one

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Not at all. I am pretty sure I overpaid, but I wasn't seeing much else come up for sale.i should have not taken any parts in hindsight other than the 3.4l core and instead brought the price down.. Hopefully this formats okay, I'm on mobile. 2001 996 manual coupe - no original engine or trans 3.4 core motor with heads partial (didn't know how big of a deal that was 2.7 3 chain spare motor with one cylinder exploded Boxster s 6 speed manual trans An extra set of two way power seats Paid 7600 delivered. It was filthy with dirt.

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Not at all. I am pretty sure I overpaid, but I wasn't seeing much else come up for sale.i should have not taken any parts in hindsight other than the 3.4l core and instead brought the price down.. Hopefully this formats okay, I'm on mobile. 2001 996 manual coupe - no original engine or trans 3.4 core motor with heads partial (didn't know how big of a deal that was 2.7 3 chain spare motor with one cylinder exploded Boxster s 6 speed manual trans An extra set of two way power seats Paid 7600 delivered. It was filthy with dirt.

I think you did ok. Mine is a runner but high miles and will need a lot of similar work, you�ll come out well ahead of me but I have some smiles in the bank already.

I think its pretty good. I always assumed 996s with blown or missing engines should go for 7-8k. In your case you got more than 996 with missing engine, so not bad at all. Hope you'll get it running without spending much more.

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Well, maybe not... Just those sport seats alone I've seen go for $5000 on BaT when in decent shape. Ya yours need some work, maybe new covers, but you can get nice aftermarket OEM type covers relatively cheap. You say you've got another set of seats...You want to sell them..? Good luck with the build, sounds like you got it under control... keep us posted.

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Ha, that's actually much more than I thought they were worth. The other set I got is black Porsche-crested two-way seats, I believe. In a little better shape on the bottoms, but uppers have some wear in the bolsters. I'm facing a new problem, whether to sell my nice seats and keep the not-so-nice ones or rock the nicer sport seats. I'll have to think about it and let you know. The main concern with the sports seats is that the bottoms are dried out. The passenger has a crack, and I yet to even sit in the driver's seat other than steering it off the trailer because I'm afraid it'll crack.

Well, heads turned out well. I made a YouTube video about it, but I am not sure it can be posted here. He had to shave off just a little for clearance on one of the caps; other than that, everything turned nicely.

Good luck with the rebuild! Be sure to post progress!