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?

[Bill Douglas]

My vote is to stay with the 3.0 and get the top end rebuild done. Going 3.2 introduces lots of other things you may not want such as the chip and getting it to interact with the rest of the car. Plus you could get a 964 cam while it's apart.

[porterdog]

Known good fresh engine vs. 90 day warrantee scrapyard unit?

Easy choice IMO.

[911pcars]

$8K sounds a little high for just a "top end valve job". Perhaps the shop is planning to delve deeper into the engine or estimating the inevitable slippery slope for you, or they have a 3.2 waiting for a customer.

Sherwood

[Porsche2217]

I would keep the original 3.0 engine for resale value, specially with the high crazy prices these cars are reaching original is important. look for another quote to do the job.

[Trackrash]

I agree, 8k for a valve job sounds really high. I would want to see a break down of the costs and get a second estimate.

You may also want to do some research on a 3.2 upgrade. There are a lot of "small" items that need to be done which will really add up. For example cutting the transmission bell housing to accommodate the crank position sensors and re-wiring the engine compartment.

[wayner]

Known good fresh engine vs. 90 day warrantee scrapyard unit?



Easy choice IMO.

If you made this thread a pole, I think this answer would have the most votes

[Shaun @ Tru6]

3.2 & harness is a $5500 to $6500 proposition and you can install it in a weekend, lot of information here on how to do it. If you can take your engine out, you can install a 3.2. It's a very easy job.

[boyt911sc]

Originally Posted by Shaun 84 Targa

3.2 & harness is a $5500 to $6500 proposition and you can install it in a weekend, lot of information here on how to do it. If you can take your engine out, you can install a 3.2. It's a very easy job.

Shaun,

What's the guarantee that the $6500 Carrera replacement engine won't need an engine rebuild pretty soon. Unless you buy a known engine, you are buying something that might need work too. Specially an engine sitting on a pallet.

Tony

[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?

[Shaun @ Tru6]

Hi Tony, I just bought one for $5500 plug and play. I was able to drive the car and run compression and leak down prior to dripping it. I would not buy an unknown engine. Who you buy from, records and numbers are all good indicators of health.

3Ls have great bottom ends so a top end is a good fix but you still have CIS and less power.

[HarryD]

If the problem is truly just in the heads, I am very suspicious of the cost numbers. Rebuilt seems high and as noted above, engine swap seems low.

To renew your heads, they need to R&R the engine, remove the heads, get them renewed, and reinstall them. To my way of thinking, 30 hours labor plus parts (gaskets, oil return tubes, chain ramps etc) and machine work on the heads. The mechanic doing the work should warranty his parts and work as well.

Ask him exactly what goes into the $8,000. How deep is he diving? Do you get new Pistons and cylinders? New rod bearings? etc.

[Flojo]

I'd rebuild the 3.0

Upgrade oil pump, cams, etc.