Exhaust Manifold Installation Help Needed
 

I'm getting ready to install replacement exhasut manifolds. Project is on a budget becuase of other issues si I'm using GLM manifolds with 3" riser blocks and Mercruiser stainless steel elbows. Closed cooling system.

So the questions--

1> which Manifold gasket that should be used between manifold and head?

2> surfaces on manifolds, riser blocks and risers are all painted--what surface prep is required on these surfaces before mating?

3> gasket configuration to be used between manifold and 3" riser blocks and sealant used there--if any. (these will aloow closed cooling water to circulate from the manifold thru the extension blocks

4> gasket configuration to be used between riser blocks and risers and sealant if any (these will have solid stainless plate beacuse raw water exits cooling system hre to go overbaord with exhaust.

5> can stainless steel studs/nolts be used to connect the risers/blcoks to the top of the manifolds?

I know this seems like a lot of nits but we got into a big long (expensive) discussion last time around about sealnts and gaskets and got some really conflicting advice from Mercruiser, Barr, MarinePower to name a few.

What we did has held for 4 years but things have changed also. Seems like there was a bulleting back then from Mercruiser about the best gasket sealer to use--in my senile state I can't remeber the whole circle-jerk we went thru.

Thanks for any thoughts and advice. I want to get all the materials together and rehears this a few times so I only have to do it 3 or 4 times to get it right.

Re: Exhaust Manifold Installation Help Needed
 

Manifold/riser installation tips:

Paint all exterior surfaces (unless you get the OEM ceramic coated manifiolds).

Don't use the paper gaskets that come with aftermarket Manifolds, use OEM Mercruiser gaskets. Much easier to work with (remove).

All gasket surfaces need to be flat. If the paint is flat, you don't need to remove it. If you have to scrape the paint off to be flat, scrape it.

NO sealer on gaskets, liquid thread sealant (not teflon tape) on anything that threads into the manifold (plugs and studs or bolts).

Chase all threaded holes with tap before assembly. Use new grade 5 (not stainless) or better bolts/studs or clean threads throughly.

When using the 3" riser extensions, don't mount the risers with long bolts. Use grade 5 or better studs and nuts. With no riser extensions, use grade 5 or better bolts.

Thread two 3/8" studs with slot cut in the end into the head to hang gasket and manifold while installing mounting bolts. Then remove studs with screwdriver (using slot cut in the end) and install last two mounting bolts.

Dave

Re: Exhaust Manifold Installation Help Needed
 

Check the inside of the GLM manifolds. I'm planning on using them when I replace mine in the spring, but I've heard a few people complain about excessive casting flash inside the manifolds. You might want to clean that up before installing. I know I'll be checking mine out. I also use a liquid gasket/thread sealer on the bolt threads only (not the gaskets), and I've never had any trouble getting them out at a later date. The stuff I use is OMC branded, but I know Mercruiser makes it too.

Re: Exhaust Manifold Installation Help Needed
 

I've got the 4 manifolds but only taken one out of the box. The insides are extremely well finished--seems like some sort of coating inside. In fact the exterior finish is well done also--especially as compared to the OSCO's that are on engines now. These also seem lighter than the OSCO's/

I'll inspect the rest of them in the next day or two.

The stainless steel elbows and the riser extensions should be here tomorrow. Next step will be the plumbing fittings, anodes and the drain plugs.

THanks for the heads up on inspection.

Re: Exhaust Manifold Installation Help Needed
 

Dave N--FYI--had to send the B&G Engine Sys back to them under warranty. Turned out the thing was defective. They have now sent it to England to further test and repair. Hope I get to see it in boat before the season is over.

Re: Exhaust Manifold Installation Help Needed
 

I'm glad to hear the manifold looks good.
They say those manifolds are hot dip galvanized, then the outside is powder coated. I also hear they're lighter because of the lost foam casting process (more accurate).
What are those stainless elbows costing you?
When I replace the manifolds, I'd like to run something better than the stock risers.

Re: Exhaust Manifold Installation Help Needed
 

Dave's right on the money for your installation as far as I'm concerned. The studs with a slot are a great trick and make the job soooooo much easier. Without them, you'll be cussing. Sometimes you run in to a little clearance issue with the bolts, but hopefully that won't be a problem for you.

Good luck.

Re: Exhaust Manifold Installation Help Needed
 

Dave, Why not use stainless bolts? Curious. I am talking about securing the exhaust manifold to the head.

Re: Exhaust Manifold Installation Help Needed
 

The manifold I unpacked and examined does seem lighter than I expected.

I got the risers from Don's Marine Salvage in Clearwater/St Pete. They are an institution and have a website think is www.donsmarinesalvage.com

Re: Exhaust Manifold Installation Help Needed
 

Dave, Why not use stainless? Curious why not in a marine environment. We are talking about the header attaching to the head, right?

Re: Exhaust Manifold Installation Help Needed
 

I read somewhere in my research that the stainless and the cast iron have different coefficients of expansion (expand/contract at different rates) which cause a variety of problems--none are good from what I read.

I just told you more than I really know.

Re: Exhaust Manifold Installation Help Needed
 

I have heard similar things, thats why I would say not to use stainless.

That explains all the trouble :( Hope it all works out.

Dave

Re: Exhaust Manifold Installation Help Needed
 

Galvanic corrosion. Dissimilar metals corrode quickly when in contact, even stainless. Plus, it's hard to know what grade of stainless bolt you're getting. There's stainless and then there's STAINLESS!!

Re: Exhaust Manifold Installation Help Needed
 

Why would you bother slotting a stud and then remove it and replace it with a bolt? Just use the stud and put a washer/nut on it. That's the way I always do manifolds,,,,,,, the end bolts where the gaskets hang get replaced with studs/nuts,,,,,, forever. The only thing you need to make sure of is that the studs are fully engaged. Double nut 'em and thread 'em in. :cool:

Re: Exhaust Manifold Installation Help Needed
 

Poorsche,
Did you go there directly to pick them up, or did you order them through the web? I did a search on the site, but didn't find much. Also, if you don't mind me asking, how much did he get for a pair?

Re: Exhaust Manifold Installation Help Needed
 

I've been to the yard a number of times. Billy had shown me the parts the last time I was there. I just called him and verified stock status and he shipped UPS with a VISA>

He's a great guy (Billy) and like his Dad, he knows where everything in the place is and what they will sell it for.

They are tough negotiators but gentle persuasion can be useful--and they have the goods. The website is really just a telephone number listing--there isn't any real detail info there.

Re: Exhaust Manifold Installation Help Needed
 

Understand. Not using a cast iron (merc style) exhaust. Using the KE cast Aluminum. Now, is it OK to use the stainless (real stainless) bolts in this application?

Re: Exhaust Manifold Installation Help Needed
 

We're finally installing the GLM exhaust manifolds. First problem is several of the bolts thru the manifolds into the block don't want to come out. We had a wrench and long extension and still can't get them to trun out.

Any "special sauce" or trick to use? Of course the problem bolts are on the monifolds on the insed of both engines.

Thanks--

Re: Exhaust Manifold Installation Help Needed
 

If the risers have been leaking externally and the heads of the bolts are rusted away - it's easier to cut them off with the engine out. Though I've done many with the engines installed - it was a real pain. Once all the junk is knocked off with a punch or air hammer - I grind the remaining bolt head off with a die grinder and lots of stones. I shy away from taking a torch to them inside anyones boat. I've done them hanging in the air - but only as a last resort. On almost all of them - once the bolt head is gone and you can remove the manifold - the remaining studs will generally come out failrly easy. They're hardly ever stuck in the head - but stuck in the manifold itself.

Do not use stainless to attach the manifold to the head. You can't maintain the proper torque. If the risers don't leak - the factory bolts work just fine.

If a manifold is leaking on the outside - it's time to replace.
Period.

Re: Exhaust Manifold Installation Help Needed
 

Thanks for the feedback--we douched the bolt overnite with some CorrosionX and this morning they came out (with some sweat, blood and extreme profanity).

Got two of the new ones on and two to go--

The other day someone with a project boat wanted some used manifolds. The OSCO's we took off my boat really didn't need replaced--they were Fresh water cooled. I saved them in case someone still needs them.

Also a two pair of Mercruiser stainless 4" elbow's we decuded not to use if anyone is interested.

Again Thanks for advice.

Re: Exhaust Manifold Installation Help Needed
 

Poorsche, I might be interested in the elbows.
Are they the cast stainless ones, or tubular?

Re: Exhaust Manifold Installation Help Needed
 

The Elbows I have are the cast stainless steel version. They look exactly like the cast iron--BUT they are solids stainless. One of them is new, the other three have minimal use and I'd rate them as 8-9's.

By the way--I've got to shed myslef of a garage full of TRS stuff an d orther unfinished projects. I've sold my warehouse.

Have 5 TRS inner transom assemblies, 4 Gimbal housing/Outer assemblies, 4 Exhaust extensions (8" long), 2 dual oil coolers, 4 TRS drives--all in need of lower housings, and a pair of TRS external steering wing plates.

If you have a need or know of anyone who does--share the info.

Re: Exhaust Manifold Installation Help Needed
 

I already have a set of the cast stainless ones. I'm looking for tube type ones. I'll keep the parts in mind in case I hear of any one who needs anything. I work a side job at my friend's marine repair shop, and you never know who might come by needing something.