Replace Exhaust Manifolds on Mec 8.1 - tips and tricks anyone??

rondds

rondds

Well-Known Member
Oct 3, 2006
8,859
Jersey Shore
Boat Info
2001 380DA
Engines
Merc 8.1s (2008)...Hurth ZF 63 V-drives...WB 7.0 BCGD (2013), Garmin 8208 & 740 MFDs, GMR 24xHD dome
Been through this with my previous boat, with Gen IV 7.4s. Pretty simple, though awkward. These motors spook me a bit, mainly b/c of all the sensors and computers. I have all the parts, gaskets and replacement sensors. Anyone do this and have some pearls of wisdom?
 
Then I have to worry about turbos and intercoolers. This is easier and way less expensive!
 
These are very heavy and hard to hold get gasket lined up and bolts started. Get you a couple of bolts a little longer and cut off the heads. You can thread in one on each end. Slide on gasket then manifold. Then you can start a couple of bolts then remove studs. Much easier.
 
Mike, thanks - I'll take that under advisement.

Outlaw, had studs for manifold replacement on my previous boat (those were standard SAE) for the reasons you mentioned. Ordered short M8 (or was it M6?) studs for this job.
 
Gotta say, I did them on my 330 Sundancer and really didn't find it to be too difficult. Granted, a second person would have been helpful when handling the manifolds, and you need to be pretty flexible to reach all the bolts, but other than that, just take your time and be sure to keep everything clean and properly torqued.
 
I JUST finished this. Not too bad at all. Here's what I did. Drain manifolds by pulling bottom hose.
-Remove both tubes feeding the vera lifts.
-Remove engine covers.
-Remove all elbows. be careful to pull them off straight up and over, slowly. They still have water in them. Dump out.
-Pull the port engine, starboard manifold first. Now you can walk through.
-Pull the Port engine , port manifold. Now you can still see how it is all configured since your starboard manifold is still on.
-Install Port engine , port manifold.
-Pull Starboard engine, port manifold.
-Install Port engine , Starboard manifold.
-Pull Starboard engine, Starboard manifold.
-Install Starboard engine, Starboard manifold.
-Install Starboard engine, Port Manifold.

Make sure all surfaces are clean. No need to remove the paint on OEM Mercruiser manifolds. Also buy the retro kit. You get a bunch new parts. Here is the best price I found.


http://shop.nuwavemarine.com/engine...manifold-866178a02-water-rail-conversion-kit/
 
mnm...thanks for the info. DARN! I already got the manifolds - Around $480 a piece, and they come with the gasket. I plan on reusing the turbulator and the fasteners, replacing all gaskets, the water drain thingies and the temp sensor. I already had some gaskets and one sensor, which I bought thinking I'd have to pull a manifold when I replaced the generator.

THANKFULLY, I have plenty of room to roam in the ER of this boat so sequencing of which to do first is not an issue. I had that problem with my previous boat and one reason I chose the 380 over the 340 (and I LOVED the 340) was engine room space!
I still need T-rex arms, but I can stand btwn them and outboard of them.

DSCN2013_zpsea142dab.jpg
 
Your not going to get the turbulator off without ripping it apart. They cost $45 each. Sorry..
 
I plan on reusing the turbulator. Not going to happen, your find them eroded.
Easiest way to install manifolds are:
tying a cord to them and lowering them to install the bolts.
using 2 long studs to guide the manifolds on.
No matter how you do it, install the end bolts loosely first , pull manifold away from the head and slide the gasket into place. The 2 end holes will need to be notched for the bolts or use header gaskets that come with the notch.
Highly unlikely for a re-use. I can get you a better price on the dry joint gaskets.
PM me
 
OK, so if I get the necessary turbulators and don't recycle, how many additional gaskets do I need? Seems that the turbulator has a gasket on each side, embedded.

DSCN1907_zpsbda3b28b.jpg
 
Hmm. Mine doesn't have the riser. Get a turbulator ( comes with gasket on each side as you said ) This diagram doesn't show them together?? and #14

https://www.marineengine.com/parts/mercruiser-sterndrive-parts/81l-inboard-ho/0w690000-thru-0w697153/exhaust-manifold-elbow-and-riser
 
So you didn't need any separate gaskets? Just the turbulator (?) If so, then I'll need one gasket each manifold, btwn the top of the riser and the elbow...I think
 
Got it. Thanks!
 
Torque spec on the manifold bolts and on the elbow/riser studs? Anyone?
 
mnm
I had the owners manual in pdf but NOT the shop manual. That is a GOOD GET! Thanks. Seems it can't be downloaded though :-(
 
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