[mbardeen]

I've got my car moving under its own power again, but it's producing a lot of white smoke at startup. I'm just running water now as coolant and the level does seem to drop. I took it out on a short test drive, and the temperature started to climb fairly rapidly as I was climbing a hill in 3rd.



I noticed the fans not coming on, and diagnosed that as a bad temperature switch in the radiator, but with all the other indications, I think I can safely say that my headgasket is blown.



Given the car's unknown history, I'll take the time now to have a valve job done. What parts do I need for such a task? I assume valve guides, head bolts & washers. What else should I provide the machine shop?



I'll update the variocam chain and pads while I'm there.



Any gotchas that an amateur wrencher should look out for when changing the head gasket? I know the basics, eg. torque the bolts correctly in the correct order, do it carefully, etc.



Edit: Any chance not having some of the vacuum tubes hooked up (like the AOS) would cause the same symptoms?



To answer my own question: http://www.968forums.com/topic/9290-vacu..._findpost_

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[Cloud9...68]

Sorry to hear about your continued troubles. The head is held down by studs, not bolts; changing the head nuts probably isn't necessary, as they look like they can hold up the Brooklyn Bridge, but if it makes you feel more comfortable, go ahead. You will need valve guide seals, and you probably ought to replace the valve cover gasket and spark plug seals (a one-piece unit). I would also replace the Variocam check-valve o-ring (Sunset has them).



Are you planning to do the job yourself? If so, you'll definitely need to read up on how to time the cams, as that's a bit of an involved procedure, which requires some special tools, including an air compressor. Same goes for just removing and re-installing the cams - you really should use the cam hold-down blocks described in the manual. Overall, R & R'ing a 968 head is a pretty time-consuming, exacting job. Read through the manual carefully, as it covers most of the procedure pretty well. If you take it to someone, make sure they're familiar with the procedure, which may be a bit of a challenge to find in Chile, I would imagine. Best of luck.

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[mbardeen]

I confirmed, it's definitely not the AOS vacuum line.



At this point my funds are tight, and if I'm going to R&R the head I feel as I might as well do it right. I do plan on doing most of it myself. However...



I've got other priorities. Like a garage to house the Porsche, and to house the tools I'll need purchase to fix it (including an air compressor). So I think the Porsche will have to sit as she is while I take care of those other priorities. That gives me some time to save, scrounge and plan.



At least I know that it goes -- now I get a feel for what else it needs. Like front shocks and wheel bearings. And probably clutch. and... and...



Just have to repeat to myself "long term project car... long term project car...".



Edit: Err. Yes, I actually meant nuts, but wrote bolts. I was planning on getting the cylinder head gasket set from Paragon. I have already installed the valve cover gasket set, but having extra gaskets can't hurt.

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[MB968]

Sorry to hear of your new issues, particularly with the logistical issues you face being in Chile. I'm not that familiar with them, but I know there are tests that can be done to check head gaskets for leaks. Maybe someone else can shed some light on how to do a coolant system leak (into the combustion chamber) test.

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[mbardeen]

Thanks for the concerns. I think I've found a way around the logistic nightmare of customs, I should know in the next few days.



I'm going to get a compression tester, but what I think what I really need is a leak down tester. My main worry is that it's not the headgasket but a cracked head. That would be very bad. Anybody have a good way to distinguish between cracks and head gasket failures?

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[AJG]

It's a real bar steward when you can't get out driving, that's what its all about. Right? Its ironic that plans for a gagage means ths car doesn't get fixed. Weep in silence.

[quote name='AJG' timestamp='1340531388' post='128532']

It's a real bar steward when you can't get out driving, that's what its all about. Right? Its ironic that plans for a gagage means ths car doesn't get fixed. Weep in silence.

[/quote]

Gagage Andy? Really? Sorry about that I'm a bit tired.

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[rl968]

Smell the tail pipe, if it smells like antifreeze, it's the head gasket.



Mine went on me last year. You dont see much of these going on these car, but I suspect we will as age catches up. I think my mechanic put a wildfire gasket on.

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[MB968]

Don't know if you can still do this today, so travel at your own risk. Years ago, you could take the radiator cap off. And, if you had a bad compression leak into the coolant system, you'd see bubbles in the coolant. I don't think this is a foolproof test, but know it worked sometimes.



And, I agree that you probably won't get a lot out of compression test, unless the leak is really bad. It's easy enough to do, so could be worth checking all the cylinders this way in case it shows something. Much better to do a leak down test. And, I think there is also some kind of pressure test for the coolant system that could also show issues.

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[mbardeen]

I do see bubbles in the coolant with the overflow tank cap off. Basically everything I see is pointing to a blown headgasket or cracked head. What's funny is that the smoke comes after a few minutes of warm-up. Perhaps the cooling system needs to be pressurized?



I've got the details of a good machine shop here in Chile (in Santiago, of course). They do cylinder heads of all sorts there, including from airplane motors. I'm assuming they should have a test to check for cracks in the block, and maybe even repair them.

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[Scott Collins]

Sorry to hear about the problems - Hope for the best but plan for the worst is my motto.



I would buy new nuts to re-torque the head. One of the special tools you will need as a torque angle wrench. It's not so much a wrench as an adaptor that you use to measure the amount of travel of the wrench when torquing the head. I did it last summer with the help of Pete Fitzpatrick of RS Barn.



Do you have a PET catalog of Porsche parts for the 968? Do you have a 968 Workshop Manual? You will need these.



Since you are in a "long term" mode, take time to order everything you need. There are many seals, gaskets, hoses, etc., associated with replacing the head gasket.



When I did my project, I decided to do the entire top end, and I also replaced the oil cooler gasket and seals, and coolant system hoses. If I had to do it all again, I would pull the engine and work on it out of the car. But it was the first time doing it and I underestimated time and effort to do the project.



One of the challenges for you I imagine is going to be having everything, every little part, on hand. Even the smallest little washer can bring things to a dead stop if you don't have it. And for you, it could be days and weeks until you can get it, right?



Just give a shout if you want more info.



Best.



Scott

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[mbardeen]

I do have the PET and the workshop manual, thanks. Otherwise I wouldn't even think of starting this task.



If I have to do so much work on the car, I want to do it right. I had planned on pulling the engine in a couple years anyway for a general refresh, so I'm now leaning toward sooner than later.



One of the reasons I want to build the garage before diving into the engine is just the issue you mentioned, Scott. I think I've managed to find a reasonably cost effective and less timing consuming way of getting parts into the country, but there will still be about a 2 week lagtime (slightly better than the 4 week lagtime I had with previous methods) for any missed parts. Leaving the engine out and exposed to the weather (& dogs) for so long doesn't sit well with me.



I know of a place here that sells the angular torque wrenches (and I already have a full range of ratcheting torque wrenches), so that's not too big a worry for me. The cam hold-down blocks are a question.. should I have them milled by a friend with a CNC machine or are they cheap enough to buy?

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[Cloud9...68]

As far as the cam blocks, if you can have them milled by a friend, you're probably better off than buying them. I haven't priced them, but being a Porsche specialty item, they're probably very expensive.



In addition to the blocks, you'll also need some long threads that screw into the spark plug holes to pull the cam blocks down. I bought some threaded rods, along with four of the cheapest spark plugs I could find. I destroyed all but the threads of the plugs, and had a co-worker with a welder weld the spark plug threads to the threaded rods.



As Scott says, there are a lot of special tools and such that you need to do this job, and it will take you some time to gather it all together. As he says, take your time and make sure you have everything you need before tearing in. But as you say, you first have to determine whether you have a bad head gasket, a cracked head, or a cracked block. I wish I had some advice as to how to distinguish among these...

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[Ryan]

Matt..the special cam hold-down tool looks easy to make. I saw a guy weld a couple spark plug ends to some all-thread rods to make his (just for the threads). Then you just need a couple blocks of aluminum with indents for the cams and holes for the rods to go through. The tool just screws into a couple of the spark plug locations.

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[Lear35A]

I have to admit I STILL don't see the deal with these cam blocks. I've installed/reinstalled my cams at least 5 times in the last couple of years without them. I just slowly brought them into place with the bearing housings. No damage, no fuss, no expensive cam blocks.

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[mbardeen]

Knowing myself, I'd mess up and scratch a camshaft or something without the tool (heck, maybe even with it). So I'll make up my own and go from there.



One thing I did notice is that when I pulled the throttle body, the seals there weren't in good shape. Could it be possible for the throttle body to leak enough water into the intake manifold to mimic the effects of a blown headgasket?



Given that replacement seals are two weeks away, is there anything I can do to eliminate this as a possibility, like maybe a bypass for the cooling hoses?

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[banditsc]

The coolant lines into the throttle body are there to prevent icing. So if you don't have an issue with extreme cold temps, you can connect those two hoses together to bypass the TB. I did that on my car.

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[mbardeen]

Cool. Those two hoses would be the two outside ones? I'll try that tonight to see if the situation improves any (not that I'm actually expecting it will).

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[banditsc]

Yes the two outer ones, you can leave them spliced together if your not worried about your throttle body icing over, which I'm assuming your not down there. All it's doing in a hot climate is warming your throttle body.

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[mbardeen]

On the coldest mornings, it maybe gets down to around -4C, so like 25ish F. And it very rarely snows, maybe once in a 100 years or so. And even then, I probably won't be driving the Porsche, so icing not much of a worry. I'll splice it and leave it. One less thing to go wrong.



However, for air flow issues I'll order up replacements for those seals, just to ensure no air is getting past.

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[MB968]

I don't get the cam blocks either. I've done cams a few times (on other engines). You just need to take your time with small amount of tightening at each cap, one after another.

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