Power & Heat Exchangers

[kach22i]

Everyone seems to agree that upgrading to SSI's and sport mufflers or something called a pre-muffler willl give you a performance increase. So...........

Imagine this: Some shop (proclaimed Porsche expert) drills holes in your heat exchanges after your rear oil cooler fails. They claim they did it to let the oil drain out that got in there (how the heck could that happen anyway?).

So now you have heat exchangers with holes in them, and oh yea they take off your blower motor and hoses and don't replace them because you dont want to spend another $300.00. They cover some of the openings with "Aluminum foil" no kidding!

They say the exchangers will smoke a lot at first as the old oil burns off, they did their best to steam clean them. However they seem to smoke after heating up real nice and stoping for a while. Also you can see old oil in places, making you wonder how bad was it before?

After driving the car a couple of weekends you become increasing convinced that low end power is compromised, and the RPM needle just dosn't flick up to red line like it used to. Yea I took it back once, a three week wait, they re-did the ignition timing for some improvement. They did not touch the cam timing from chain tensioner upgrade they did.

Drum roll.......the question is: If finely engineered and installed heat exchangers give you a performance increase, then drilling holes and leaving holes open will degrade performance, right?

I kid you not, this is a true story.

The reason I am asking, is it will take more money and grief to figure out if the shop also screwed up the cam timing. I am hoping its only the damage they did to my old and leaky carbon monoxide belching heat exchangers for the performance degration.

Any theories out there?

PS: The mechanic that repairs my other non-Porsche car drove my 1977 911S 2.7L, before and after the other shop did the work. He said I have a claim, there is a definate loss of power. However there are so many details and variables to this story, that I want to exhaust all posiblities. I hate being wrong, I hate being the bad guy.

[Jim Sims]

I hope they only drilled holes in the air shroud around the actual exhaust pipes - this is probably what they did. Stupid but not fatal. Your performance degradation is likely due to other causes. The exhaust doesn't go through the shroud, only air from the engine cooling fan. This will make little or no difference in engine performance nor should it increase the CO that one is getting in the cab. Of greater importance is what they've done to the air flow from the fan; the nozzles to the heat exchangers must not be left open as these become paths of less resistance and the cooling air will leak out there instead of blowing over the cylinder, heads and engine mounted oil cooler. They can be blocked off but not with aluminum foil. Get a new shop pronto. Jim

[kach22i]

The holes they drilled must be in the outer jacket of the heat exchanger only, because it sounds the same.

The drop off of performance is not great, but it took a lot of the fun out of the car. Like I said, my regular mechanic drove it and noticed the difference right away. The guy who did the work, said this is a good as my year gets, he is happy with the way it is running. Well of course he is happy, anything less would cost him more time. They already had to correct the ignition timing once. I have zero confidence in any of the work they did. If I wanted it done wrong, I would of did it myself.

They could of did a bad job of adjusting the valves, or messed up the cam timing when doing the chain tensioner upgrade (or damaged the valves I have read) or even something when they removed the smog pump. Heck, they may of even put the wrong spark plugs in. They are screw ups, how they have a good rep, is beyond me. Never go to EuroTec of Ann Arbor.

At this point, the car is livable, but disapointing. Having a new shop check all the work of the old shop and getting a lawyer or small claims court (up to $3,000 in Michigan) is not how I want to spend my summer.

I am thinking of driving the car all summer (after I install a new shifter), and in the late fall getting the car re-timed (cam, valve and ignition) while I have it in for the heat exchangers. I don't need heat in the summer anyway and will have cash on hand to get the work done. I might even have the 2nd to 3rd gear syncro/sleeve replace while I am at it.

One thing at a time for now.

[chrisp]

Sounds like some of the theories you have are not only detrimental to your butt-dyno but also to the engine. Incorrect plugs, bad timing, bad valve adjust, incorrectly blocked off air ducting, etc. could lead to significant engine damage.

If you are thinking about legal action it doesn't help your case to wait 4-5 months? How does anyone know that in the meantime another shop didn;t make some mistake and you are looking for Eurotec to correct the problem.

Personally I wouldn't drive it in that state of tune for fear of damage nor would I run the risk of a business not being around in 4-5 months to take legal action.

Now for your personal safety you need to fnd the hole in the exchanger and determine without a doubt that there is not CO dumping into your heating system.

[Morrie]

Trivial maybe... Boil down basic theory is that the cooler the better for the air entering carbs or FI, and the exhaust the hotter the better.

Is it possible that by venting your heat exchangers that your exhaust temp dropped off?

Maybe a dumb thought, but I haven't seen the holes! Take some JB weld and close them up, see if it makes a difference....

Just a rambling thought from a 912 guy...

Best,
Morrie in Texas

[MotoSook]

Whoa!!! First what did the wrench do to the car besides drill holes in the tin surrounding the exhaust pipe?

The holes in the tin alone will not degrade performance on the car. I don't imagine they are big holes, but it is still not desirable. I would make the shop replace it. Claim potential CO poisoning and a large medical bill or property damage or human injury should you pass out at the wheel. That will scare them. There is no reason they should have drilled into the tin. Esp. if they had the headers/HE's off the car! A good used replacement would be adequate...

What else did they do while the car was in the shop? You mentioned changing the cam timing...why? Did the shop break the engine down?

You need to provide more history if you expect good advice/opinion.

[kach22i]

Originally posted by Souk
Whoa!!! First what did the wrench do to the car besides drill holes in the tin surrounding the exhaust pipe?

[chrisp]

WOW you had a lot done. Looks like you got some pretty good labor time quotes. Especially .50 hrs for the pedal bushing replacement. The clutch cable one is a little questionable at 1.3 hrs since they had it removed anyway. Parts prices aren't that bad either considering you went through a shop. Was your oil cooler leaking? That's the most painful part of the whole bill. No new clutch either. Interesting.

Isn't it crazy how the "while you are in there" bill can grow so fast?

So the suspected timing miss is from the tensioner upgrade.

[mudman]

It is hard to see, but what is with the 8 exhaust gaskets, and 3 different types? I could see 8 gaskets but only two types. So did they remove your HE's? If they charged you for gaskets they would be just a little hard to install with out removing the HE's, so it seems as though the holes drilled were useless.

About CO: the turbulant air under the car will allow some exhaust gases in the holes if there is neg. pres. in the HE's. But I see in the notes that they state the HE's are rusted out, so that makes the holes irrelavent (as long as the rusted out bit is the surrounding metal of the heat exchangers).

Let me know if you ever find a good shop in MI, I sure haven't yet.

-Jeremy

[MotoSook]

I don't think that's a good invoice, but I'm a cheap bastard....

Where they saved him some time, they screwed him on others....90+ dollars for a pop-off valve! 1200+ for an oil cooler! 300+ for plug wires!

2 hours to check his clutch action?!?!?!?!

Mind you that some of that work was done with the engine on a stand! I hope they used a stand...

...some of the shop owners can speak up, but the invoice total is what I would pay for a good (almost excellent) '77!

Sorry "kack," but that's my honest opinion....you did wanted honest right?

I'll never make money for a shop as a service writer....

On topic...it doesn't look like they dug into the engine internal, so it is likely a poorly tuned CIS/ignition that is making the car seem different.

[Jim Sims]

"3 different types"; the 2.7 liter engines have a third type of exhaust joint (has three bolt holes) between the thermal reactors (or three to ones) and the heater boxes. This joint uses a triangular shaped gasket different from the others. However, if the exhaust system was off, the count should be ten gaskets unless they reused a couple of them. It should be understand that the heater boxes or heat exchanger sheetmtal shroud is not gas tight even when new; if fits closely but still has enough of a gap to allow air and gases to leak in and out. Afar bigger source of CO is when the car is idling and the wind drift is unfavorable. The exhaust can be pulled right up into the back hatch intake grill and pushed in the the cab by the engine cooling fan. Jim

[chrisp]

Souk, I am like you...a cheap bastard and a total DIY when required. But we have the space, time, competancy, and the interest level that others may not.

This BBS is great for people who are about to have work done. It's a wake up call for those who have already had it done and paid more than they could have (again assuming the four points above). I am a softy for the people having the wake up call.

-Chris

[cstreit]

FOUR HOURS to replace oil return tubes?!!!!

They sold you the collapsable ones. With those this is a 30 minute job, especially since they had the heat exchangers off already.

It really looks to me like they charged you the book rate for everything, even if the labor for somethign had to be done for another line item. THese might be the book rate for the standard ones, but NOT collapseable!

Not everything was outrageous, but on this one dude, you got hammered. I would call them to task on that one. Hell, if you want, I'LL call them and ask!

[palle7688]

If they changed you tensioners they might have mistimed your cams, that would decrease power and possible ruin your valves.
They could also have bend your valves while timing, have a leakdown check performed.
If they had your HE's off, why didn't they just steamclean them?
Sounds like a bad shop.

[azasadny]

$117.90 for spark plugs? I know of a shop in Ann Arbor, MI that I won't be going to for any work on my car!

[vash]

i think your board name fits, because you are definately stuck in a tough place. maybe it is time to buy some book and some tools and go for it your self. i think most of the stuff on the reciepts may seem scary, but in reality, is a piece of cake. how about driving it for the summer to get some damn enjoyment out of the car first. when i drop my exhaust to change into some SSI, you figure out if our exhaust are compatable, and you pay for shipping to the shop of your choice. nothing else. no holes in mine...

[kach22i]

Originally posted by palle7688
If they changed you tensioners they might have mistimed your cams, that would decrease power and possible ruin your valves.
They could also have bend your valves while timing, have a leakdown check performed.
If they had your HE's off, why didn't they just steamclean them?
Sounds like a bad shop.

You hit the nail on the head, this is why I am putting all the cards on the table with a new shop - still looking. I don't trust EuroTech to correct their own mistakes (they had a shot at it already).

My first concern is: was the cam timing messed with inadvertantly while upgrading the tensioners. That would be neglect, verses abuse if they bent valves in the procedure. Either way, I need another shop to verify my fears, or tell me relax they only put the wrong kind of plug in, or other stupid goof.

Now I remember why I used to make car payments and pay through the nose for insurance. New cars don't make you deal with frauds as much- they have a warrenty.

[MotoSook]

No no "kack".... this incident should not be a deterant. Owning an air-cooled 911 can be a lot more joy than pain. You just ran into the wrong service guys...

You will learn a lot here and on GruppeB ( www.gruppeb.org .... bring your '77 to the Dark Side). In a few months, you will be helping others and driving your car on the track..and wishing you had not tried the "track crack."


I and a lot of guys here and on GruppeB have spent a lot of money on our cars, and we continue to do so...happy as a blind pig in a bowl of *****

But! I bet most of us would turn away from a car payment for our beloved 911's. As much money as I spend on my car, it's elective. If I didn't own my 911, I'd have bought some hot sports car and be making payments on it...not so elective sometimes.

And warranty work is not guaranteed to be good work either....you still have to find a trusted mechanic.

[palle7688]

I'll agree with Souk, You just ran into wrong shop.
On the other hand, these cars can be expensive to get up to good standard if they have been neglected. And when you finally get a good car, there's allways something to improve.
Like a well without buttom.
But I guess that's called customizing and thats also expensive for newer cars.
My P-car is possibly more expensive to run compared to to my everyday/winter car, but I enjoy very second in it. And as a hoppy you spend whatever is needed. I'm on a budget, but my hoppy gets high priority.

[toolman]

Hey Kach, Next time you need work done, give me a shout, I'll work for half that price!!