[apex]

Been away from the forums for a while - and holy heck... I come back and see Dan's sobering timing belt failure thread.

Ha. Well after a cool 50k (I was asking for it) my timing belt stripped out about ten teeth at the bottom. To save some bucks and to learn a thing or two about the car, I'm taking on as much of the heavy lifting myself as I can - then relying on local racer expertise to recondition my head, get the re-installed cam timing right, & etc.

After two days of work over the holiday weekend, plus a couple of evenings I almost have the head off. That exhaust manifold is a pisser. [img]style_emoticons/<#EMO_DIR#>/tongue.gif[/img]

My car is in the 120K range - so the While I'm In There List is not trivial - I'm trying to keep it as short as possible. New pump, seals, oil separator (see below), and so forth.

Lots of pics to follow.

Commenting on the other thread's discussion of "what's it like when your timing belt goes" I can say it's a much more subtle, and lethal, drama-free failure. The car just stops. In my case, at a stoplight. The engine *does* sound different when cranking trying to re-start - more clangy - the sweet sound of valves clanging on pistons. I initially thought it must have been failed DME. When my A/C compressor clutch froze - *that* was much more dramatic.

Consistent with another poster's experience - the top rear timing belt cover bolt holes were, uh, stripped/corroded/exploded. Weird.

I have some questions for you quys. My cam gears look pretty good. Pads are worn but not scarily so. I'll replace them.

It's usually a mistake to post multiple questions inside a single thread - but this is a friendly group here. Let's see what happens.

First question: The valve cover was ahem.... scary brown. I'm extremely envious of the pristine camshafts posted here by others!~ My mechanic thinks the oil separator is bad and blowing all kinds of doodoo back through the system. Intake manifold interior, injector tips are really gummy. I've used nothing but Mobil1 as long as I've had the car. What do you think?

Second question: The cams are off. Damn. The variocam unit is a muscular little fellow! I need some advice on how to compress the variocam pistons together enough to get the chain off the cams. I've tried squeezing with a vise between two blocks of wood, but it seems to stop with about 1/2" to go - not enough slack to get the chain over the gear cogs.

Cheers,

Jeff in VA

   
   
   
   
   
   
   
   

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[apex]

Kinda quiet around here. Guess this ain't a mega-thread after all. [img]style_emoticons/<#EMO_DIR#>/biggrin.gif[/img]

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[flash]

lol - i think we were all waiting for more from you

i think it takes some special tools to get the variocam and chain out of there, and i'm not sure you can do it without removing the cams

i'd call pete

as for the gunk, you clearly have a lot of crap in there - the injector looks nasty - if i had to guess, your engine is very tired, and everything was blowing past your valve guides - from the pics, the cams look worn too

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[Ryan]

<b></b>Not what he wanted to hear, I bet.

Seems I remember the vario unit coming out with the cams and chain as a unit almost.

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[flash]

i asked pete about this a couple of hours ago - confirmed - cannot remove variocam without removing cams - of course he would have to do that to remove the head anyway

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[apex]

Well that's true: variocam and cams come out as a unit. Ah, to be a "friend of Pete." Perhaps I should ring him up and introduce myself?

You don't need any special tools to remove the variocam and cams. You do need a special clip to hold the variocam pistons together once compressed - this will allow for reassembly. The clearances seem very tight, though, in terms of getting the cam chain off over the gear teeth.

At this point the head is off.

As for my "very tired" engine: perhaps so! But my mechanic says the pistons and cylinder walls all look good. That's a subjective visual judgment but he's seen a lot of porsche engine in his day - so without a leak-down test we really can't say. Flash is right, of course: it's all getting in there somehow. New guides are coming with the new valves.

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[flash]

lol - true, you don't need them to remove it - you need them to reinstall it

pistons and cylinder walls do last a LOT longer than the head - when i said tired, it was really about the valves and such - it looks like a lot of unburned fuel - a leakdown test would have been the first thing i did though before yanking the head - that would tell me how far i needed to go

at this point, do the head and cross your fingers - you could be fine - many people are - if there is no scoring of the walls, and your oil pressure was good, then you should be

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[xrad]

Nice to see some pics of the insides,,,,keepa goin...

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[rxter]

<!--quoteo(post=75248:date=Jul 9 2009, 03:53 PM:name=xrad)-->QUOTE (xrad @ Jul 9 2009, 03:53 PM) <{POST_SNAPBACK}><!--quotec-->Nice to see some pics of the insides,,,,keepa goin...<!--QuoteEnd--><!--QuoteEEnd-->

voyeur...

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[xrad]

I was getting tired of posting big picture threads...nice to see someone else pick it up!

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[apex]

xrad - I got more where these came from.

I should probably post this question in a new thread but in the spirit of "mega"

Has anyone replaced the water pump studs? Anyone replaced them with stainless steel? How does stainless react with aluminum in a glycol environment? I'm asking for the obvious reason: mine are very rusted. Can't stand rust. [img]style_emoticons/<#EMO_DIR#>/angry.gif[/img]

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[flash]

short answer - yes

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[apex]

LOL! I was looking for the long answer - sunset says they don't have 'em listed - the joke there is for the want of a water pump stud porsche would have you buy a new block.

I'm sure something can be found locally with the right threads that fits. And then there's the problem of removing the rusted originals.

Flash have you sub'ed in stainless?

By the way I spoke with Pete at RS Barn today - I may be sending him my head for some quality R&R. He says it's not uncommon for engines with this mileage to look like mine does - its a function of the design, not necessarily a flaw in any component. We'll see after we take a good hard look at the guides and such.

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[Cloud9...68]

<!--quoteo(post=75316:date=Jul 10 2009, 05:53 PM:name=apex)-->QUOTE (apex @ Jul 10 2009, 05:53 PM) <{POST_SNAPBACK}><!--quotec-->By the way I spoke with Pete at RS Barn today - I may be sending him my head for some quality R&R.<!--QuoteEnd--><!--QuoteEEnd-->

Are you having Pete do the standard head refurbishment, or one of the upgrades?

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[xrad]

get phosphate free antifreeze and low h2o content. I usually run almost 90% antifreeze...yeah, I know what they say about that. never had any corrosion or rust problems

or overheating.

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[flash]

yeah, that's a bad idea - i learned this one decades ago - my dad used ran an antifreeze packaging plant for about 20 years (you'd be amazed at how many brands are all the same) - lol - over the years, i had the "advantage" of learning all about ethylene glycol

it's got nothing to do with corrosion or rust - you won't get the cooling capabilities - i realize that it raises the boiling point more the higher the percentage, but it won't extract the heat - the whole purpose of a coolant is to transfer the heat to the coolant, then pass it through an exchanger - if the heat doesn't get pulled away, you'll eventually do damage

50/50 is the best mix

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[xrad]

Yep. I knew "someone" would have to talk about the heat capacity of water v. EG.

So I say what I always say:

1) What is the actual water content in off the shelf EG? Most are premixed or have some water content (which is not always shown on the label)
2) An EG solution with 50% h2o has a specific heat capacity of 0.85, and at 100% pure , it is 0.65 (So yes, H20 obviously has superior heat capacity)
3) What is the volume of the system?
4) what is the pressure of the system?
5) What is the system flow?
6) what is the ability of the system to extract heat?

In a cooling system that has minimal flow, minimal capacity, minimal heat extraction ability, and minimal pressure...then NO, do not run pure EG(likea closed maring system).
In a system that has extra capacity, cooling, flow, and heat extraction, AND you don't want corrosion: I run EG at least 70%(allowing for the water in the off the shelf coolant).

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[xrad]

I know I said 90% above in the first reply.

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[flash]

i'm really puzzled here

this is what i've learned and what EVERYBODY says - regardless, i spent a half hour yesterday goggling around, trying to figure out why anybody would do that, thinking maybe something new had come up, but i found nothing - what i did find was endless data on the 50/50 wisdom

i don't know where you got any info that indicates that running more is better, or why you would want to do that to begin with - it's not like you love on venus and need a higher boiling point

can you explain?

what temperatures does your system run at normally and under load - i currently run at 170-185 degrees normal (depending on ambient temp), and 205 under extreme load - all at maximum of 16lbs pressure

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[xrad]

I guess you can't believe everybody...

I had steel/iron wet liners in several prior engines. I did not like the corrosion that 50/50 or less antifreeze produced, really bad crusting on the aluminum as well as aluminum erosion where there was gasket contact. Also, these were Italian engines and the aluminum block, and steel/iron of the liners, and engine water pump/thermosat bolts as well as the gaskets tended to fall apart and corrode very easily.

So I researched the mixtures in several engineering/chemistry books and on-line. I pulled apart two of my rebuilds using the full strength mix after two years for one and three years for the other. No corrosion and they looked like the day I built them. Just a little slimey residue on the inside. Additionally, one engine sat for almost 1 year on blocks. So, the liners were exposed to O2 as the fluid level of AF dropped in the block. Again, NO corrosion (aluminum OR steel). The alcohol of EG must have wicked up the outside of the liners and protected them.

Additionally, these engines were run hard and (with a new radiator aqnd h20 pumps and hoses) never ever ran hot.

Read the reports on EG protection. Increased boiling point and decreased freezing temp reaches max at about 70+% mix with a little sacrifice on cooling.
I agre with this. But if your cooling system can handle the slight extra heating and disperse it, why not get max corrosion protection. I feel that the corrosion I witnessed before using at least 70% mix was probably due to free radicals generated by the breakdown of the extra water. Of course, it could have been from the EG....but since no new gross corrosion was in the teardown engines, I believed it was the water. Now maybe purified water has slight advantage, but if h20 goes through steam cycle if any air gets in the system will, in my opinion , cause corrosion.

Anectdotal, yes. True fact, yes. This is what I do. Maybe there is another way.....

Running engine hard with many shifts and full throttle revs, usuall, it runs between 9-10 oclock mark, cools down to below 9. I don;t have an accurate temp guage hooked up at moment.

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