308 Engine Rebuild

What do you mean by exposure, the cost of an overhaul, or the value of the car presently?

We need some pics of the car and more information, how bad is the motor etc....

 

A competent mechanic could rebuild a 308 motor easily with the right tools,the right workshop and spare parts manuals,help from members on this board.Its basically pulling it apart and putting it back together.I would have a competent head rebuilder rebuild the heads and the same with the block.

 

A big part of the cost of having an engine overhauled is getting it out and putting it back. It's not difficult, but it is time consuming. You could, as an alternative, consider pulling the engine/transmission yourself and then delivering it to a mechanic who will do the engine overhaul for you, and then put it back in yourself. That alone would probably save you a couple of thousand dollars, and if you enjoy doing that kind of work, it's a great way to learn the ins and outs of the car. If I can pull the engine on a 308 and put it back, anyone can with a little help, some basic tools and an engine lift, and the determination to do it. It's really not that hard to do.

 

What is your definition of a 'competent DIY'? If you've successfully rebuilt fairly modern DOHC car or motorcycle engines than you could probably do most of the rebuild except for the head & any machining on the block.

If you don't have rebuilding experience, then consider doing as FasterIsBetter suggests, pull the engine & have a shop that's done F* rebuilds before do the rebuild, then you do the reinstall. You could consider pulling the heads & separating the engine from the tranny yourself.

There are some past threads covering some parts of a rebuild, but no threads that cover redoing the bottom end, or complete details on how to rebuild a head. The factory WSMs assume a highly skilled factory trained technician who just needs specs, tool p/ns, etc. They're a help, but nowhere near complete enough to get you thru the project.

 

sent the engine to "newman" and let him build a monstro at a fair price! send him a p.m. for his thoughts.

pcb

 

Sell me if before you part if out.

I'll buy it as is

Sean

 

what is the cost of a rebuild/overhaul? 10-15K?

 

Okay if I'm not mistaken, aren't the fiberglass 308's rare?

 

Best advice here. If you do not have experience building engines then a 308 is not a good place to start. The cost of a learning mistake is just too much. On the other hand you can save a bundle by pulling the motor yourself, cleaning it well (all labor you will otherwise be charged), and sourcing all the necessary parts. Leave the disassembly and re-building to experienced hands as it is money well spent. With that said a Ferrari dealer is by no means your best bet. In most cases specialist independant shops will do a much better job for much less money as they are experienced with dealing in 308's every day. The dealer only handles the new stuff and unless there are some really gray haired techs there, they will be learning on your car. Good luck with the project.

 

Good for you but had to ask

Pressurizing the cylinders migh work but the front exhaust bank springs/seals won't be easy to get to in the car

Good luck

Sean

 

Don't sell the car. They are great cars. Just need a little TLC now and then.

AFAIK, you can't do the valve seals on the 308 heads without pulling the heads off. The "rope trick" you are describing is something that old mechanics did to get the heads off. If all else failed and you could not get the head to separate from the block, the story goes that you would feed rope into the cylinder near the top of the compression stroke (need to be sure both valves are closed, or you can bend a valve), and then crank the engine to TDC to push the head up and break the seal between head and block. I never tried it, but an old Jaguar mechanic friend of mine said he learned to do that in the 60's and it worked on the old straight 6 Jaguar blocks and heads. But it is not the recommended method by any stretch of the imagination.

What is the symptom that you are experiencing with the engine? Some blue smoke at start-up? Unless the valve seals are completely gone, you shouldn't be having much smoke from them. If compression and leak down are good, just get out there and drive the engine. Also, try some of that Castrol High Mileage 20W50 motor oil. It has seal conditioners that might help. Heavier weight oil will leak less when the engine is sitting. Whatever you do, don't use synthetic as it tends to leak more.

p.s. There is also a method for changing a rope seal on the rear main of some older engines using a tool called a Sneaky Pete, but that has nothing to do with valve seals.

 

No, the rope trick is used for doing valve seals, I have NEVER heard it used as a way to push the head off. But hey, we heard it here first, it might actually work. Though I would be curious how much torque one would have to lay into the crank to do it.

I wouldnt even consider doing valve seals with the engine in the car. Schedule an engine out full major service and take care of it then. Just remember that the rings can only handle so much oil. If they are getting enough to make it burn excess amounts, you can be sure its clogging up the rings with carbon and sludge. The sooner you resolve the issue the better. If you block the engine with a particular piston on TDC, with the cams out you can pressurise the cylinder to keep the valve from falling. I never did think stuffing rope into a combustion chamber was a good idea, it could loosen up carbon and let it get down between the piston and rings, and thats the last place you want any grit. Just because something works, doesnt always mean its the best way, or that it wont have negative results later down the road.

 

Search the body of text in the old Fchat archives for 'valve seal' and 'replacement'. I'm pretty sure I remember a couple of threads on replacing them w/o pulling the heads.

You can readily buy adapters that fit in a spark plug hole & let you use compressed pressurize the cylinder, thus keeping the valves closed. Even if you accidently bump a valve, there's enough pressure & air flow that it will close immediately. Hmm, A leak-down tester might be able to be used to pressurize the cylinder. I've used this method for 30 years to change seals on various cars, starting with an XK150 Jag. but haven't had to tackle a 308. Procedure is roughly:


Pull the cams on the bank you're working on (or on both banks).

For each cylinder on that bank:
- Pressurize the cylinder to 50-60 psi.
- use a tool to compress the valve's springs enough so you can remove the retainers,
- ease off the pressure on the springs, & remove the springs.
- Replace the seal
- reinstall the springs & retainers.

Repeat for all valves on that bank.
Put the engine on PM1-4
reinstall the cams on that bank
install a new timing belt & tensioner.

Repeat for the other bank.

Suspect doing the front bank's exhaust valves is going to be a PITA. You'll need to come up come up with a spring compression tool that works in tight places.

 

i have just done mine, its easy, the engine is such a basic engine ,even the valve timing so easy,go for it

 

ps .dont try the old rope trick, you may bend a con rod

 

I have had this work for me on every car I tried it on (about 10 so far) that smoked on start up and/or used oil. Two in particular, a Honda Civic, and an Mercedes 300E both had over 150K miles at the time. The Mercedes itself, I had every local area dealer tech I spoke to swear up and down it needed valve seals, almost a dozen different factory trained techs. The 300E was using a quart every 350 to 400 miles and loading up at long stop lights, smoking on startup, etc.. The Honda would fill the yard with giant clouds of smoke for about a minute when cold, and was also using a lot of oil.

The 300E had records back to new, 7500 to 8000 mile oil changes with Pennzoil 5W30 until I bought it with 165K miles. As much as I wanted to believe all those guys, I just felt the motor was probably just gummed up in the rings.

Buy a can of Gunk Motor Flush and two quarts of Marvel Mystery Oil. Change the oil and filter, and replace two quarts of oil with 2 quarts on MMO and drive it very easy for about 100 miles without stopping. With it hot after running it, change the oil and filter, and run it a few more miles (about 10) on fresh clean oil, and with it warm, not hot, shut it off and put in the can of motor flush. Run the car at a slight fast idle (dont drive it or rev it) for 5 minutes, shut it off and change the oil and filter again. The car calls for 10W50, I would advise you use it, at least through this procedure, but in any case, from this point on do NOT add oil when it uses some. When it drops to the add line, change the oil and filter each time. If its the rings, which I suspect it is, it will probably stop smoking right away, and will stop using oil by the second oil change. Instead of using expensive synthetic oil, you can use dino oil for all these oil changes (Castrol 20W50?) and until it stops using oil, and go back to synthetic afterwards.

The 300E never used oil after that even to 3500 miles between changes. When I sold it the car had 195K and ran like a top. The Honda never smoked or used any oil afterwards either. If it really is guide seals and this procedure dont work for you, the worst youll have is a motor that is spotlessly clean inside when you take it apart to work on it.

Resist any thought of not changing the filter in this procedure. If there is anything inside the engine that could plug up the filter, it will bypass unfiltered oil throughout the engine. If you really want to see something, cut the filters open after you take them off and inspect the pleats (which you should be doing everytime you change filters anyway), youll probably see a lot of gunk on the filter.

 

Wrong. The "rope trick" is indeed a way to replace the valve stem seals without removing the heads. The reason for this is to keep the valves from dropping into the cylinder head once you remove the keepers. The idea is to fill the compression chamber with rope (or air, using a compressor with proper fittings), that way the valves stay in there fully closed position and do not drop down into the compression chamber, allowing you to replace the seals.

If the car is just smoking in the morning it is probably just the valve stem seals. If it is smoking all the time it is more than likely the rings which would necessitate a full rebuild.

 

Ummm, what are your rods made out of... tin foil? You are suppose to use soft 1/4 inch nylon rope. I doubt that you would create enough pressure to "bend" a rod it is simply meant to keep the valves from falling into the compression chamber.