308 valve seal replacement

I am wanting to replace my valve seals. I have read through many threads and see that this is a common problem on 308's causing the excessive oil consumption and the embarrassing cloud of smoke during a warm start. I don't believe my engine has ever had them replaced but since it runs so perfectly, I wanted to simply change the seals while doing the belt service without a full engine removal. I am very concerned about the limited space on the front bank (cylinders 5-8). I feel like this is a possible task but don't want to be in the middle of it and find out otherwise. Has anyone done this? Is this a crazy idea without removing the engine?

 

Forgot to point out that the car is an '81 2 valve.

 

I should start by saying it's my understanding the injected 2v cars had an oil consumption issue from the get go.

As far as replacing the guide seals is concerned, I highly doubt it is possible to replace those with the engine in place as even with the engine out it is difficult to replace the guides if the heads aren't removed. However, the heads alone can be removed with the engine in situ which is what I would recommend for such a situation. Chances are very good that the guides have exceeded their service life by now, so you might as well have them replaced and have the heads 'done' in general as replacing the guide seals alone over old and probably bad guides is like putting a band-aid on a gaping wound, and it would burn oil anyway as those seals wouldn't last long in those old guides. Machine work for the head/guides (including new valves, guides, seals, cutting the seats etc) is about $1500-$2k.

 

Thanks for the response. I would actually prefer to remove the heads but I read a couple threads that indicate the head can't be removed with engine in place since there isn't enough clearance. Apparently the heads don't have enough room to go over the studs. Can this really be done? If so, is it practical to do it without engine removal?

 

I'm currently doing the heads on a '76 308/GT4. The engine is out, and the heads are off. You could use pressurized air or the old rope trick to keep the valves closed, but I don't see any way you could get a tool on the front exhaust bank to depress the spring and remove the keepers, let alone see what you are doing. I agree with John - if you can get the heads off in situ, that's the way to go. Otherwise, pull the engine - it's not that hard.

If you are going to replace the guides and seals you might as well replace those sodium-filled exhaust valves while you're at it. you might want to look at my thread here: http://www.ferrarichat.com/forum/308-328/458208-observations-gt4-engine-pull.html to see what's involved, and my progress on the head work. There are several other threads on the topic. as well. Lots of info available.

 

When the cars were new getting the heads off in place was very easy. They come right out. Alloy heads on steel studs that have been assembled for 30 years? That's a good one. That will be a mother of a job with the engine on a stand.

 

You would know better than I would, but I haven't had nearly the issues with 2v heads as I have with 4v heads. 4v, engine out and a head pullers is practically required. 2v, usually not.

 

at least it will fix the 2v oil consumption problem - did on mine. jon s

 

It doesn't look there is enough room for the front head to clear the studs before hitting the firewall. If by some miracle there is enough room, there's no way it's "easy." Heck, getting to all the exhaust header nuts alone isn't easy. It looks impossible, but if it's not, there's no way it's easy.

 

It clears. Loosen the 5-8 header from all attachment points and there's sufficient room there, then remove the intake manifolds. The big question is always if the heads are fused to the studs as they more commonly are with 4v motors.

 

Thanks for the advice. I plan to take this on by the end of January. It looks tight but I will go will do some yoga to prep for the flexibility needed! With any luck, the heads won't be stuck. I just know that if I take the engine out, the project will last into driving season and don't want to risk it. More to come I'm sure.

 

Do yourself a favour and consider the option of removing the engine. Allow me to sell you on the following merits:

1. Engine removal and replacement on a 308 is not that big a deal. Budget one day out and one day in. It can be done on jack stands in an average garage.

2. The likelihood of your heads being stuck is very very high. If this is the case you will burn tons of time fighting with the heads and will likely end up pulling the motor after wasting days contorted, bruised, bleeding, and beaten.

3. If all you want to do is replace the seals then with the engine out you have lots of space and options for doing this job without removing the heads at all. This saves the huge job of pulling stuck heads, cost of head gaskets, & (if you choose to change them) head studs.

4. Your major service will go MUCH faster and easier with the engine out.

5. With the engine out you have the option to change hard to reach hoses in the engine bay. Hoses that would otherwise be next to impossible to change become the job of a few minutes with the engine out.

6. Having the engine out lets you clean both the motor and the engine compartment with ease making for a nice detailed engine bay.

Planning is key when working on these cars. Removing an engine may sound extreme but it is nothing compared to the pain of fighting stuck fasteners with next to no access. Most people don't get this and prefer to trickle away huge amounts of time rather than just commit to a more encompassing plan that in the end takes less hours and certainly less heartache to achieve.

Lastly be sure to research Viton valve seal options. I believe BMW seals work on the 2V heads and they are much better than what was offered by Ferrari.

 

This is the kind of apparatus you will likely need to get the heads off. A massively difficult job.

The exhaust valves are already an accident waiting to happen. If you are going to the trouble of removing the heads, you will be doing yourself a big favor by replacing them with new stainless steel valves.
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Tim and Rob are both correct.

Take it out, clean it up, service it and replace the exhaust valves.

 

Ok, I'm convinced and after a hard look at it, agree that it makes sense to take the engine out and allow me to do this right. As I look under the car, I notice that it is almost impossible to take out the front bank exhaust manifold. For those that have removed the engine, does the front bank manifold stay on during removal? It appears that there is enough clearance but wanted to solicit your advice. Thanks.

 

Mike Florio, I am reading your post on the headers and can't imagine how you got them off prior to removal. I think there might be more clearance in the 308 versus the GT4? Not sure but wanted to acknowledge your excellent documentation on the "GT4 engine pull" thread. Thanks for the great reading!

 

I left the front bank manif in car, just dropped it down, when removing the engine. If difficult, lift the engine a bit, unbolt and drop down the manifold. Rear bank manif should be removed upwards before starting lifting the engine. Remember, cover rear window with wood. One slight hit with the engine and the window will be broken.

/Peter

 

The method I used, after reading all the posts on engine removal, was to disconnect and remove all the exhaust components aft of the header downpipes. Then we removed the rear header after disconnecting and moving the e-brake rollers and cable.

To remove the front header, first soak the nuts with penetrant (I like the SeaFoam product) for about a week. Then crack all the nuts with the engine in situ, but leave the header in place. On the GT4 the engine must be hoisted from the front and rotated out of the engine bay. As the engine is hoisted, when the header just clears the deck remove the nuts and the header just drops out through the bottom. This photo shows how the lifting strap is wrapped around the front head just prior to the lift.
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