Engine work

david911 · 12-02-2002, 05:59 PM

I have decided to have some work done on my engine now, before spring autocross and nice weather. The engine has loss of compression in 2 cyls, and bad leakdown (80%) in those cyls. The leak is coming from the exhaust valve and the rings. The engine seems to be running fine, however.

The mechanic is going to take things apart in order to see what is wrong. The thought is that valves will need to be replaced, at a minimum. His estimate is $7000

The $7,000 breaks 50/50 into parts and labor. Here are the big ticket labor costs:
1) Valve grind, replace valves and springs as needed $2600
2) Replace head studs labor $250
3) Engine R&R $400

On parts:
1) ARP rod bolts and head studs $750
2) Valve springs (EBS) $530
3) Exhaust valves $740
4) Intake valves $650

I understand the ARP rod bolts and head studs. The valves and springs are also upgrades. I believe the valve springs are titanium, and the valves are sodium filled? I am not clear on what these enhanced valves and springs get me (more durability for sustained high-revs?

Note that these costs do not include new pistons and cyls should that be needed.

Does this work sound reasonable? This car is driven mostly on the street (with vigor!) and autocross. I have interest in DE as well.

Any thoughts would be appreciated!

David

Doug Zielke · 12-02-2002, 06:20 PM

"The leak is coming from the exhaust valve and the rings."

This "estimate" is so full of BS, I don't know where to start.
The best advice I can give you, is to find another mechanic before your bank account bleeds to death.

dtw · 12-02-2002, 06:31 PM

This could be something as simple as a couple stuck chunks of carbon. Not probable, but possible.

The labor prices aren't way out of line. The parts are. Can't imagine all valves need replacing, and there's no need for the ARP hardware and titanium springs unless you are building a race engine.

You don't mention what kind of engine this is, what the maintenance history is, or what the mileage on it is, to give us some context for your current compression and leakdown figures.

Need in-put!

david911 · 12-02-2002, 06:55 PM

The engine has 100,000 miles, I do not have a service history. I have had 2 seperate shops do the compression and leak down, with similar results (1 cyl leaking from rings, 1 cyl from the exhaust valve). I plan on keeping the car a long time. I also plan on driving it hard, on a racetrack and autocross, not so much puttering around town (though I will be "touring" with it).

This mechanic does do racing stuff, so maybe the springs and valves are overkill. I thought pretty much everyone recommended replacing the head studs and rod bolts.

David

JonT · 12-02-2002, 06:56 PM

Sounds like a perfect time for a 3.6 swap. Sell your engine to someone who wants to do a rebuild for 2000 to 2500, buy a 3.6 for 7000, and have someone install it with a carerra style oil cooler, 993 headers and cat, lightweight flywheel, and for a few more thousand dollars than you are paying now to get your engine running properly you've got 265+ ponies screaming behind your head. It'll set you back around 10k in all. Its verrryyy worth it.

dtw · 12-02-2002, 07:07 PM

Quote:

Originally posted by david911
This mechanic does do racing stuff, so maybe the springs and valves are overkill. I thought pretty much everyone recommended replacing the head studs and rod bolts.

David

Stock springs are fine and should be replaced during the valve job. You don't need the race springs unless you are spinning race motor rpms, which given your description, you are not. The rod bolts also must be replaced, assuming the bottom end is opened up. But not with ARP, necessarily. Same goes for head studs- but you haven't said yet what engine this is. If you've got some Dilavar in there, yes, yank 'em. But they can be replaced with standard steel studs.

david911 · 12-02-2002, 07:15 PM

OK, I get it 3.2L carrera engine, 1988 coupe.

For some reason, the 3.6L swap doesn't do it for me as much as upgrading the existing motor a little.

CamB · CamB's Garage

If its a 3.2 maybe the ARP rod bolts are a good idea (apparently a weak point on 3.2s).

BK911 · BK911's Garage

I would try to get the compression back in those cylinders first. Do a search and you should find an awesome procedure described by early S man on filling the cylinders with injector cleaner to eat up some of the carbon deposits on the exhaust valves. At the very least you should try the injector cleaner in the tank before dropping the engine.

Good luck!
BK

john walker's workshop · 12-02-2002, 08:25 PM

it would be good to know the year of your car if you want an accurate assessment. 30 hours is a common labor charge for a valve grind, which includes R+R engine. @$80 per hour, that's $2400.
replacing all the valves is common practice because the stems wear out, as well as the off chance that an exhaust valve will loose it's head, due to overheating in it's previous life. the prices on the valves and springs are way too high. arp rod bolts are a good thing if you're racing. do the rod bearings at the same time. arp head studs are overkill, and not needed on a low horse engine. if you have dilivar lowers, replace them with steel. the labor price is good, if it includes R+R pistons and cylinders. more than good actually.
you should be able to get it done for just over $4000. that's VG, new valves, springs, arp rod bolts, rod bearings, lower steel studs. shop around.