rocker arm cover installation

[rebars1]

1984 Chris Craft Scorpion 230 Merc260.engine: GM5.7L (circa 1990?): I have a small oil leak where the exhaust cross-over contacts the cylinder head. I am hoping it is coming from the rocker arm cover and need to replace the gasket. The cover is the flat-ish grooved type with four bolts down the center instead of on the sides. My questions are:

1. Is there a preferred sealant should I use between the gasket and cylinder head?

2. From what I can research, the bolts should be torqued to 4 ft-lb. Is this correct?

Thank you

 

[JCF350]

Re: rocker arm cover installation

These take a "rubber" gasket and don't need sealer (I've seen some that had sealer applied and they leaked). The gasket will stretch in the groove and hold itself in place for installation.

The torque sounds about right.

 

[Mkos1980]

Re: rocker arm cover installation

If thats not it, its very common for oil to travel up the intake bolts and leak in the liffle valley or between head and intake.. Esp since you have the 72* angle intake bolts and you mentioned center area. Remove them, clean them, and then with thread sealer install them back in and tq to spec.

 

[TilliamWe]

Re: rocker arm cover installation

You've gotten two good responses so far.

Those goofy angle center intake bolts strike again?!

 

[Haut Medoc]

Re: rocker arm cover installation

Is this the Scorpion with the round back bench with the threesquare covers over the engine?......
I had one of those, I loved that boat.....​

 

[rebars1]

Re: rocker arm cover installation

Thanks for the replies. The bolt I mentioned run down the center of the rocker arm covers, not the intake manifold. I can't tell if the oil is seaping down through the cover or up through the manifol. The cross over exaust get pretty hot right there.

Here's a picture and a diagram, FYI.
http://s23.photobucket.com/albums/b365/rebars1/?action=view&current=7472290-R1-037-17.jpg


Haut Medoc: This Scorpion 230 hs a cuddy cabin and a rear seat each side of the engine cover. I've been restoring this one, completing an engine replacement the previous guy had started. I am looking forward to getting it in the water.

 

[rebars1]

Re: rocker arm cover installation

Here's a diagram
http://s23.photobucket.com/albums/b365/rebars1/?action=view&current=cylinderhead2.jpg

 

[TilliamWe]

Re: rocker arm cover installation

rebars, we knew what you were talking about. The bolts Mkos mentioned are you Intake Manifold bolts. The little bolts for your valve covers probably have nothing to do with this. Most Chevy valve covers leak at the corners, if they leak at all. Seeing that picture, I totally agree with him, your intake manifold/gasket is the culprit, not your valve covers. The bolts in the area where the paint is gone, are at a different angle than the others on that manifold.

 

[rebars1]

Re: rocker arm cover installation

Here's another picture. Thanks for the input. Are the center bolts you are talking about the ones on each side of the exhaust crosser?
http://s23.photobucket.com/albums/b365/rebars1/?action=view&current=c1.gif
http://s23.photobucket.com/albums/b365/rebars1/?action=view&current=gif3.gif

 

[Mkos1980]

Re: rocker arm cover installation

Yup, thats not valve cover gaskets. I would clean it up and try removing the 2 center intake bolts and redoing them. If it were me, I would install new intake gaskets and clean it up good. Thats what I did when I bought mine. It was a 1990 and had low hours, but it was filthy in that area. I took off the intake, sanded it down and painted it good. Cleaned the mating surface and reinstalled everything. Looks brand new now.

 

[rebars1]

Re: rocker arm cover installation

What is recommended for the thread sealer you mentioned. Perfect Seal?

 

[Fishermark]

Re: rocker arm cover installation

Permatex #2 works well.

 

[JCF350]

Re: rocker arm cover installation

Having numerous different sealers in my box I would chose the Permatex teflon (brush can) thread sealer.

 

[rebars1]

Re: rocker arm cover installation

I checked the two center bolts on each side at the exhaust cross-over and found that they were not very tight. I removed and replaced them, one at a time, cleaned the threads, applied Permatex #2 and reinstalled them to 30 ft-lb. When I ran the engine, there was still a little bit of oil seaping out from the top of the gaskets, (between the gasket and cylinder head).

So, I guess it is time to remove the intake manifold and replace the gaskets. Is that a DYI thing, or do I need to take it to the shop?

 

[Mkos1980]

Re: rocker arm cover installation

DIY. If your good, you can get it done in about an hour and a half assuming you;ve done it before and giving a few minutes to clean the head of old gasket. But if you've never taken one off before it could take you an afternoon with bolting it back down and stabbing the distributor back in, redoing the timing and linkage. Its pretty basic. Get yourself a service book and if you cant find a marine one, your next closest will be any auto with a 5.0 or 5.7 V8 87-95 It will give you the basics.

 

[rebars1]

Re: rocker arm cover installation

I have the Mercruiser Service Manual #2 that I have used for my boats with 888 and 225 (Ford 302) set ups. It also has a section for MCM250 GM5.7 V8, but not specifically a Merc 260 setup, which is what this boat started out with. I believe the engine is circa 1990-1994 (carburated). Would the torques and procedures be pretty much the same as for the MCM250?

Per the Merc Service Manual, for reinstallation, it looks like I should use Perfect Seal around the water ports and between a seal and a gasket, but should a bead of sealant be used between the gaskets and the cylinder head? If so, what kind?

 

[Mkos1980]

Re: rocker arm cover installation

I dont run any around the intake ports at all. Just a tad around the coolant ports. As for the mcm250 it will be the same.

 

[rebars1]

Re: rocker arm cover installation

OK, I pulled the intake manifold. The oil looks clean. The gaskets are a little crusty around the cross-over ports. A few chunks of gasket dropped, but I was able to get them.

A few questions:

1. The gasket set I got did not have seals for the front and back. What is the best RTV sealant to use? The existing sealant is gray colored (Volvo RTV?)

2. From the responses and the Merc manual, no sealant goes on the two gaskets, except Perfect seal around the water ports (I assume both sides of the gasket)

3. does any sealant go around the distributor hole?

4. Should I use Permtex #2 on the bolt threads, or something else, (Locktight)? Does the sealant affect the torque specification?

Thank you

 

[Fishermark]

Re: rocker arm cover installation

1.. Use any good RTV you want. They sell a silver that I have used and works well. One tip on the RTV for the front and rear: Try and put an "appropriate amount" on the block. I know that sounds silly, but in other words don't put it on so thick that it gushes out all over the place when you install the intake. On the other hand, you obviously need to put enough on so that it completely covers. I usually use a bead of about 1/8" or so - maybe 3/16" even. Then, after torqueing down the intake, take a paper towel and wipe the front and rear areas clean. That will make a nice clean appearance and ensure that there are no gaps in the seal area. You need to do this immediately before it skins over. Works well for me everytime.

2. Whatever gasket set you have will tell you what to use on the water ports - I would follow those instructions.

3. For the distributor, I normally put a little sealant between the gasket and the manifold, and leave the distributor side dry - for obvious reasons. You need to turn the distributor from time to time.

4. See all the above for the bolts and sealant.

 

[Don S]

Re: rocker arm cover installation

1. http://www.permatex.com/products/Au..._Oil_Resistance_RTV_Silicone_Gasket_Maker.htm

2. Correct

3. No, use a new gasket

4. Clean bolt threads and tap the holes to make sure they are clean then use the sealer in the link below on the threads, and torque to specs.

http://www.permatex.com/products/Au..._Permatex_High_Performance_Thread_Sealant.htm
OR
http://www.permatex.com/products/Au...tex_Aviation_Form-A-Gasket_No_3_Sealant_a.htm