Rebuild vs. Upgrade

[thorloki]

I am in need of advice.
My mechanic informed me that my 1979 3.0L engine has a burned intake valve on #1 cylinder (leak down test). Compression test on other five cylinders indicated they are within 10% of each other. The engine ran strong before this, started first time every time. I am debating whether to have a top end valve job done or sell the engine the way it is and upgrade to a 1984 3.2. The estimate to do a top end valve job is $8,000. The cost for the 3.2 is about $7,500; installation is another $1000-$1500. So out the door for the 3.2 would be about $9,000. When I work the numbers they are about break even. I have no documentation on the mileage on the 3.0l engine, odometer indicates 120,000. PO said engine and tranny were gone thru about 25,000 miles ago….don’t trust him. I can probably sell the 3.0l for high of $2,000 which would bring the bottom line cost of the 3.2 down to about $7,000. The 3.2 has 94,000 miles, leak tested, and will come with a 90-day limited warranty.
My question is: Considering the increasing cost and availability of older 3.0l parts is it cost effective to just do the top end valve job or pay the extra and upgrade to a 3.2 with 94,000 miles with a limited 90 day warranty?

[304065]

Fix the 3,0.

I can't speak to the dollar amounts but if the prices are the same, I would much rather have a rebuilt 3,0 than a 3,2 with 94,000 miles on it. And the "90 day limited warranty" frightens me.

Are you able to do the work yourself? If you can work safely and follow instructions you can save literally thousands of dollars and have fun at the same time. "Installation" of a 3,2 for 1,000-1,500, well I'm not sure what that means, does that mean full conversion to a 3,2 Motronic system, or does it mean unbolting your old CIS and accessories and putting it in the car? Need more information to advise, but a 911 engine drop is a couple hours if you've never done it before and about an hour if you have.

You will get varying advice, guys say, "go for the power" but seriously unless you plan to race it's just not that big of a deal for the street. Better to have a rebuilt 3,0 with nice high compression and reliability than a used motor that could have valve issues and has unknown condition.

my .02 which together with a couple bucks will get you on the subway. . .

[otto_kretschmer]

if the oil pressure is still ok on the 3.0, I'd just do the valve job

8k for a valve job sounds insane so I'd call around and see what other reputable shops ask

if you're up for the challenge, pull the motor and do the disassembly of the heads yourself and take the valves to your local auto machine shop for a valve job.

[thorloki]

304065 and otto thanks for your replies.
The price for the installation of the 3.2 includes pulling the 3.0, oil change and valve adjustment on the 3.2, notching of the 915 bell housing to accept sensors from the 3.2. The 90 day warranty for the 3.2 basically covers anything internal to the engine, ie rod knock, damage to valves, low oil pressure and failure of chain tensioners.

Question to 304065: Why is a 3.0 more reliable than a 3.2 Carrera engine?

[Flat6pac]

90k on a 3.2, all 12 guides will need replacing as part of a top end, always.
Bruce

[thorloki]

Thanks guys for the input.
How much for a top end valve job? Any recommendations for a good Porsche shop or individual in Orange County, California?

[Flieger]

Aase Motors or GMG

[otto_kretschmer]

Thor,

I go to a shop in Vista in the San Diego area

with jobs I don't want to do myself..

European Motorsports | Audi Repair Vista CA | BMW Repair Carlsbad CA | Mercedes Repair Encinitas CA | Volkswagen Repair Oceanside CA | Porsche Repair 92081 | Audi Repair 92008 | BMW Repair 92010 | Mercedes Repair 92023 | Volkswagen Repair 92049 | Por

ask for Joe, or Scott

I don't know anyone in Orange county but there must be someone who is good.

for generic auto machine shop work I use a place close to me in Temecula but again, I'm sure there is someone who can replace the guides and cut the seats for you in OC

Costa Mesa RD can probably do any machine work you need

https://www.youtube.com/watch?v=dncyBPHCKyQ

I've never been to this place but I like watching his youtube vids

[afterburn 549]

From things i think I know.
I would recheck the valve deal, Exhaust will finally burn, But they live in Heil !
Intakes....hardly ever.
Me, myself and i would confirm the findings. A leak dwn test is only as good as the operator.
I would redo that cylinder for sure.
If you can turn wrenches this will not be expensive , if you have to hire it out, well the labor is the same as it all comes apart .
Very slippery slope, you might as well get the most for the labor dollar.

[Robey5]

I would do the leakdown once again on #1. Seems a little ... odd ... to me.


If you have a set of tools, I would strongly recommend that when you make this decision: stay 3.0, drop the engine and trans yourself, take your time, find a reputable machine shop that you can trust - and bring the valve job to them. Then, put it back together yourself.

After all of that: you will have a connection with your car that reaches far beyond your wallet.

And ... 3.2 - with 9X k miles for a similar tab: I wouldn't bite. No way - but that is just MY opinion.

[afterburn 549]

I can do one valve for you .(it would save you tons of money and be a fix that may get you by for a long time,
..but,,,be for that, i would check and see if its a tight valve if it shows a leak again.
A burnt intake is highly unlikely , not impossible, but unlikely .

[eastbay]

Sounds suspect, I would recommend setting the valve lash .001 or .002 loose on that valve only and run it for awhile.