My experince with GLM manifolds,.....

After the latest thread about using aftermarket exhaust manifolds,...
I decided it's time to do alittle more with mine...

My 4.3LX was bought as a Frozen core motor,..
I replaced the Block,+ welded the original mercruiser manifolds,...
While the welds held just fine,.. I knew I was boating on borrowed time,..
I bought a set of GLM cast iron manifolds off ebay, from a fellow iboater, pure coincidence,... I kinda thought that it was probably the same person, but it didn't really come to light til after the auction....

Anyway,.......
I finally got around to installing the manifolds in May of 06,.... They bolted on nicely,+were run up til this last fall,...
Toward the end of last season I was experincing some Hard starting, but blew it off til I was doing my winterization.....
That's when I discovered Water in the cylinders..... Not Good....
Of course, the 1st place I looked was the manifolds,+ risers,....
The evidence was hard to see, but after careful study,...
Ayuh, It was There,... Light rust tracks....
Of course that led me to find the "Why" part of it,... After all,... Brand New manifolds shouldn't be leaking,+ the risers still Looked to be in servicable condition,....
I dug out a flat file,+ struck it accross the tops of the manifolds,.......
Bingo......... The Problem......



You can see, the manifold on the right in the picture where I filed it, the file was touching Only on the outside edges,....
The center sealing surface is about .005 to .010 Low,... While that should still seal with the gasket,.. It did for awhile.....
Looking at the manifold to the left, you can see a small rust track on it's left inner sealing surface,+ the corresponding place on the gasket......

I'm heading over to a Bud's place today,+ He's going to resurface them for me,.....
If I had to pay a Machine Shop to do this,... I probably wouldn't ever buy another set of these GLMs,...
But,...
With the somewhat Free services I have available,...
I'd buy them again, in Aluminum,+ Inspect them Much, Much more closely.....

Good Luck with Your's.........

Re: My experince with GLM manifolds,.....

Bond, we did the identical thing to my dads new GLM Aluminum ones. They were a tad off so we ran a file across until all was good. We also did teh exhaust flange. (Could have skipped that part because it was so close to being perfect) Did you run a file across the risers as well to see if they were a tad off? I know mine were, but all is perfect now.

Re: My experince with GLM manifolds,.....

That doesn't make me feel too comfortable.............I just put a set of manifolds and risers on my "new" longblock in the fall.

To tell the truth, I wasn't too impressed with the GLM manifolds...........I didn't check them for flatness but now hope they are OK

Re: My experince with GLM manifolds,.....

I'm gonna ask the dumb question - is there any chance the opposite mating surface is supposed to be curved in the opposite direction?

I'm planning on buying a log->center conversion kit that probably comes with GLM manifolds in the spring, and I was hoping it'd be worry-free....

Erik

Re: My experince with GLM manifolds,.....

Before the GLM's my dad had to get a sierra manifold for a quick trip before we upgraded this year to all aluminum. Sierras suffered the same problem. We took them to the local machine shop where he surfaced the manifold for us for 10 bucks.Lots of people say china made manifolds are bad and glm's are one of them , but sierra had a HUGE china casted right into the manifold. I accually find GLM's to be better then the sierras. JMHO

Free, what did you feel they lacked so that I can address this for the manifolds we are about to install.

For anybody else looking at this, we tested one set of GLM"S performance ones vs high doller units vs the sierras we had before and found the high doller and glms' made IDENTICAL power. (Hi dollers made 2 more lbs) Both were 10hp above the sierra (port) mercruiser(star) setup. This was on my 350 mag with a crane powermax cam, beehive spring setup, Comp pro 1.52 roller rockers and extended tipp'ed plugs (Not extended reach) Without the cam for people who do not want a cam we did 298 or 299 Fly HP with the same setup but used 1.6 RR's and a set of LT headers.

Re: My experince with GLM manifolds,.....

It is simple the milling head was NOT level when they were machined and with the quality control what it is they made it through


It is a problem with a lot of the inport machine tools and can not be fixed on many


Tommays

Re: My experince with GLM manifolds,.....

I dont even think they were milled from the factory, but I think it may be other stuff. Its high in some areas and low in others. Even if the milling machine was not level the surface would still be leval, but on another angle. I think it was just casted and maybe sanded down or something. With teh aluminum stuff it took me 15 minutes per side to fix the problem. Pretty minimal.

Re: My experince with GLM manifolds,.....

Here was a thread from my post on the new manifolds:

"OK....removed the blockage..............must have been casting material(?)

Now for the next problem..........when I install the elbow it is hitting the other pipe plug.........called GLM again...........seemed like this is NOT an uncommon problem.........I will have to grind it down.

Not too impressed with GLM..........."

The blockage I am referring to was under the pipe plug I removed to install the fitting for my FWCing hose.

Re: My experince with GLM manifolds,.....

- is there any chance the opposite mating surface is supposed to be curved in the opposite direction?

Click to expand...

Nope,.....

The cast iron Mercruiser risers are still as dead flat as the day it came out of the Mercruiser factory.......
And,....
Those shiney SSteel 1s you see at the top of the picture that are going on are Dead Flat as well......

Re: My experince with GLM manifolds,.....

tommays said:

It is simple the milling head was NOT level when they were machined and with the quality control what it is they made it through


It is a problem with a lot of the inport machine tools and can not be fixed on many


Tommays

Click to expand...

Well, I dunno. I have a mill and two lathes, all made in China. It's true that they're not as high quality as some American, German, or other western nations' products, but they can be worked with. I've learned more about trueing up my tools the old fashioned way with them that I'd never have had to do had I been able to afford "real" machine tools. That's the other thing, I'd never have gotten any tools if I hadn't been able to buy the ones from China...

I've only found one tool that I bought (my bandsaw) that's too poor a design to true up. All the others I've been able to adjust and tune so they have very little error - better than a lot of american made tools.

Erik

Re: My experince with GLM manifolds,.....

Wow! That's an eye opener! Glad you found out what the issue was. Who would have figured this with brand new manifolds?

Re: My experince with GLM manifolds,.....

Bond-o said:

Nope,.....

The cast iron Mercruiser risers are still as dead flat as the day it came out of the Mercruiser factory.......

Click to expand...

Ayuh, .....you shoulda got the OEM manifolds......

Re: My experince with GLM manifolds,.....

Eric

We just look around till we find OLD american or engish tools like the 20" lathe with a 3" spindle bore we found for 2500 dollars

It needed many repiars BUT is still a far better machine

TOS from the Czech Republic is also a high quality tool as well as many of the brands from Korea

Tommays

Re: My experince with GLM manifolds,.....

tommays said:

Eric

We just look around till we find OLD american or engish tools like the 20" lathe with a 3" spindle bore we found for 2500 dollars

It needed many repiars BUT is still a far better machine

TOS from the Czech Republic is also a high quality tool as well as many of the brands from Korea

Tommays

Click to expand...

Good for you! I'm happy with my 9x19 lathe, paid $500 for it and it does everything I want.

Re: My experince with GLM manifolds,.....

I also use OEM Volvo manifolds as well.

Re: My experince with GLM manifolds,.....

Kind of amazing. When I first started on the site, I spent a lot of time saying get OEM. Only to be ridiculed since there were so many places to get CHEAPER parts that were just as good.
Since I never used (on my boat or customers boats) anything but OEM, I finally just learned to keep my fingers off the keyboard.
Now, after working with only aftermarket stuff, I now am back on saying go OEM. It's cheaper in the long run. Of course, if you want to throw something back together cheaply so you can sell it, then by all means get the cheap aftermarket stuff. IF you want to keep the boat. Get OEM, you won't regret it.

Re: My experince with GLM manifolds,.....

Don, Have you had any experience with perfpro techs manifolds/risers? They were mercruisers R&D for over 25 years and they are right down the street from them. I usually go OEM also but I figured that I would try these as they are ceramic like the OEM's and they worked directly w/Merc so I figured why not. I haven't installed them yet but they seem ok and I put a straight edge on the surfaces and they appear to be fine.

Re: My experince with GLM manifolds,.....

Don, Have you had any experience with perfpro techs manifolds/risers?

Click to expand...

Nope.

Re: My experince with GLM manifolds,.....

In my experience, with automotive included;
Always draw a rasp across all mating surfaces before installing, it will take off hidden burrs, or it will show up a bad milling job.
new parts included.

Re: My experince with GLM manifolds,.....

Coors said:

In my experience, with automotive included;
Always draw a rasp across all mating surfaces before installing, it will take off hidden burrs, or it will show up a bad milling job.
new parts included.

Click to expand...

I couldn't agree more. It is foolish to make assumptions about something that can be double checked and cleaned up so easily. I have never installed any new manifolds (intake or exhaust), thermostat housings, risers, cylinder heads, etc, without making sure they had true surfaces first. a good straight-edge, and a light make quick work of checking flatness. I use a file or a flat-plate with emery cloth mounted on it if I have to true things up. Aluminum is particularly notorious for not staying put, and should probably be checked at least once every other season, if not every season.
--
Stan