Time to replace the valve cover gasket.

1. What is the difference between the rubber and cork gaskets?

2. The factory manual says to use a continuous 3/16th bead of RTV sealant - is a gasket used in place of this?

3. Where can I get the valve cover bolts and what size are they?

4. How can I tell if the old valve cover needs to be replaced?

5. Do the bolts need to be re-installed in a specific order? Book does say 6 lb-ft, but no order

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1984 Fiero SE

quote Originally posted by RWDPLZ: 1. What is the difference between the rubber and cork gaskets? 2. The factory manual says to use a continuous 3/16th bead of RTV sealant - is a gasket used in place of this? 3. Where can I get the valve cover bolts and what size are they? 4. How can I tell if the old valve cover needs to be replaced? 5. Do the bolts need to be re-installed in a specific order? Book does say 6 lb-ft, but no order

1 i have better luck with the rubber ones but they cost a lot more.
2 if you are talking about a 4 cyl i've never been able to get sheet metal to seal on cast metal useing RTV, it might work on a 6cyl.
3 did you loose them, the are kinda special and have a sholder on them. you'll have to find some used ones.
4. if you take it off, replace it. (unless it's rubber, you can reuse those to a point)
5. i start in the middel and go top bottom, left top bottom, right top bottom.

On an L4??? First you need to look at your valve cover carefully.

Are there dimples or a ridge along the area that meets the gasket/head? If so then you want to use a cork gasket and be really careful installing it.

If the cover flange is flat where is meets the head, you can use a rubber or silicone gasket.

GM used 2-3 cover setups. What one you have determines what gaskets you can use. The Dimpled cover was originally installed with only RTV... (Often leaking as a result.) The idea with the dimples was that they would provide thickness control for the RTV Silicone. If you use a gasket, you have to use one that the dimples can sink into. Meaning cork. Rubber and Silicone gaskets don't like these covers.

I cover some usefull things with cork etc here. If you have the dimpled cover then do not use RTV silicone with the gasket. Spray the gasket top and the flange with Permatex High Tack sealer. Apply the gasket to the cover and then spray the bottom of the gasket with high tack. Everything has to be VERY clean to get a good seal.

Use the teflon tape on the bolt threads so they won't back out. You need very little pressure to seal the cork.

The best gasket if you can get one has metal inserts that keep you from crushing the gasket or warping the cover. These can only be used with the "flat" covers.

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Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurasic Park)

The Ogre's Fiero Cave (It's also at the top of every forum page...)

GM even used different valve covers for the same engine and yr model-or at least they did for the 84 2.5s. Janes 84 has the flat flange which allows me to use the 'good' rubber gasket with the built in spacers. My 84 has the flange with the dimples-which means I had to use the cork gasket. Even then, I had trouble with mine. The cork gasket seemed to have shrunk up a little and didn't want to stay in place in the corners, even when using the fast tack. Perhaps it had sat on the shelf too long before I bought it. It took several tries before I got it to seal on the right front corner.

One of the projects I intend to try someday is to take an extra valve cover, & spotweld or braze a 1" sheet metal strip forming an inner lip all around the 2.5 valve cover protruding down to the same dimension as the outer lip. I want to make it like a Detroit Diesel valve cover-if you've ever seen their construction. It does 2 things. It keeps the gasket from being squeezed to the inside of the cover, and prevents any oil at all from ever coming in contact with the gasket except that which may be thrown upwards. Detroit Diesel covers seal very well-especially considering the 2-4 hold down bolts are along the centerline length of the cylinder head, with no bolts at all around the outside.

Here's a tip if you have a V6 on replacing those gaskets. It don't take much to have the gasket fall out of the cover while you're trying to get it in place so you may want to use this method. Put the gaskets in the valve covers and then cut maybe 4" lengths of very thin wire (22 G, garbage ties etc) Put it through the bolt holes and give it a twist. Once you have the cover in place, simply untwist the wire, pull them out and put the bolts in. Takes all of 2 minutes to setup.

If you have the V6 I THINK you need the rubber gasket. I just finished replacing mine today and made the mistake of getting the 2.8 universal intake & valve cover gasket set. Well, the cork gasket doesn't fit the aluminum valve covers for the Fiero 2.8. Therefore, I ordered the Fiero specific valve cover gaskets. Those fit.
Hope this helps,
Craig

MJ...

Mitsibishi used a 2 bolt aluminum cover on the engine in my Caravan. That's all that holds it... Two bolts in the midle. If the gasket isn't cooked out, you can even reuse it. Nice since it has solid rockers that need fairly regular adjustment.

Walling around the inside might help. The oil that hits the gasket isn't pressurized. What the L4 could use more is a CNC cut ring you could drop over the cover flange to spread the bolt load. (This would also mean you need longer bolts.)

All...

Any one that has the dimpled L4 cover should head for the salvage yards and find a flat one whenever possible. This engine was used in allot of FWD cars so finding a cover isn't very hard. If you have a flat flange that is abused you'd be better off finding a good one than trying to straighten it in allot of cases.

The main leak problem problem with cork is caused by:

1. The gasket was crushed durring installation.
2. The gasket and mating surfaces were not clean.
3. The bolts backed out.

# 1 is all too common. Usually means the cover gets mangled as well. I'd say use load spreaders like some other engines but several bolts are in places where that isn't posible on the Fiero L4 and many other covers.

# 2 applies to all gaskets. Even ones that go in dry. If the surfaces are slick with oil the dry gaskets can move and of coarse oil/dirt messes with any sealer you may be using.

# 3 happens with valve covers pans etc when using cork or other resiliant gaskets without the bolt hole inserts. If you don't use something to hold the threads the low torque simply lets them work loose. Since I started using Teflon pipe seal tape on the bolts that has been much less problem. Plus the thread sealer serves as an anti sieze when bolting into aluminum like the trans pans. (This helps seal out water where the bolt hole goes thru the aluminum and is exposed to the elements.)

You have to be careful with sealers on some "rubber" gaskets. Some are actually silicone and if you put sealer on them you'll cause them to leak later. Other ones that are actually rubber can usually be used with Permatex High Tack spray to hold them in place for assembly. You want to use only enough spray to make them sticky. It doesn't take much. Never use RTV silicone sealer with rubber or silicone gaskets unless specifically directed to do so.

[This message has been edited by theogre (edited 05-29-2005).]