Riser and Exhaust Manifolds--about to replace

[MaddyDean]

Hi All

I am about to replace my Exhaust manifolds and risers on my twin 5.7's. Plan on starting the work this weekend: Remove the cover, clean things up, get electric there, and develop a plan.

Just took delivery of the parts and it looks like the only thing I forgot to order were the Drain Plug fittings. Everything else I think I got.

(I ordered two of these)
http://www.perfprotech.com/store/pr...er-Small-V8-Coated-EK-MERC-SB-C-NS,75402.aspx

I have easy access into the EC and the engine is accessible.

My only real concerns are:

1. Breaking a bolt and having to drill it out (Engines are yr-2000 and risers/manifolds were changed once already
2. Sequence and Torque

I was told the the torque should be between 30 and 40 Lbs so thinking I will go 35 for now

I cannot seem to find the sequence.

Has anyone performed this tasks on their 5.7 and Happen to know that info? I would appreciate the help if you could forward it over.

Also, any other words of advice would be appreciated, This is my first time taking on a tasks like this but I have worked on engines before.

Much thanks

 

[cwray350]

if possable bring engine up to operating temp less chance of breaking bolts i have not broken a bolt since useing this method wear gloves also do yourself a favor use new manifold bolts they get weakened and its really a pain when one breaks going back together

 

[2000SEARAY280SS]

for the 1999 to 2001 5.7 the riser to head torque is 25 ft lbs
riser to elbow 33 ft lbs in the torque table.

later in the replacement write up the torque setting was 25 ft lbs for both

no mention of sequence and with the low setting i would doubt there is an issue.

 

[OldSkool]

Tighten the nuts evenly front to back or back to front. Snug the nuts to about 10 ft.lbs then retorque them to spec. I am not aware of any pattern for GM exhaust manifolds and I have done a few of them.

Soak the nut threads with WD40. Make sure the blower is on and all the fumes have been displaced with clean air. Warm the nuts a little with a small propane torch if you have any resistence at all.

Good luck. I will be doing the same before we splash.

 

[my3sons]

.



My only real concerns are:

1. Breaking a bolt and having to drill it out (Engines are yr-2000 and risers/manifolds were changed once already
2. Sequence and Torque

It's a judgement call on the bolts, but if they won't go, don't break them. slice the heads off with a dremel tool and then you can work on them better after you get the manifold out of the way. I don't think you will have a problem.

Rule of thumb on exhaust manifolds is snug the bolts then torque in 2 stages from center working out.
Good luck.

 

[MaddyDean]

Good feed back all. in regards to 25' lbs, that is really conflicting with what this link illustrates.

http://www.perfprotech.com/store/articles/marine-exhaust-tips.aspx

so I am torn--Going to email Merc.

In regards to cutting off the head of the bolts, that is a great idea--cool

Thanks for all of your help--I will let y'all know how it goes.

 

[2000SEARAY280SS]

I pulled the 25/35 data from the cover24 merc manual.

here is what the site you referenced quoted.

"Bolt torque should be reset after initial startup, while the engine is still warm. Refer to your original manufacturer's engine service manual for specific torque settings.

As a rule of thumb we suggest between 30 - 40 Lb-Ft for 3/8 fasteners threading into cast iron and 20 - 25 Lb-Ft for 3/8 fasteners threading into Aluminum. HOWEVER THE MOST IMPORTANT THING TO REMEMBER WHEN TORQUING MARINE EXHAUST PRODUCTS IS TO PERFORM IN A UNIFORM PATTERN IN ABOUT 2-3 SEPARATE SEQUENCES. 1) 10 LB-FT FOLLOWED BY GOING ON UP TO 15 - 25 LB-FT THEN FOLLOWED BY TAKING THE TORQUE UP TO THE FINAL RATING. THE TORQUE SHOULD THEN BE CHECKED AFTER RUNNING THE ENGINE FOR 30 MINUTES THEN AGAIN AFTER 20 HOURS. Never use anti-seize type products on bolts or studs as this can allow for loosening of the parts."

not sure if the heads are aluminum or cast iron that would drive the actual tq settings.

 

[MaddyDean]

OK I got word back from Merc and they wrote;

Manifold to block 33 - 45

Riser to manifold 25

Another question: with the gaskets, would you just put the gasket on and tighten bolts or would you use some sort of gasket sealer stuff, goop, thingy to hold the gasket in place and make a tighter seal.

BTW: Port engine Port exhaust/riser is apart--I was just going to loosen the bolts but things came right apart. Tomorrow I want to put the new one on that engine and then to the starboard engine port side.

The Starboard risers have the throttler cables and such so those will be harder.

Also changing the exhaust bellows while I am there--seemed easer enough and cheap enough.

Thanks for your help.

 

[Bt Doctur]

a trick to use replacing the exaust gasket is to notch the ends from the bottom so they slip over the bolts. install manifold with the end bolts just started. drop gasket in place , install center bolts, tighten to spec.

 

[Quint4]

deleted

 

[rondds]

Changed my ORIGINAL manifolds last winter. Broke off 5 boltheads and rounded another. Cut the rounded one off with a dremel and removed the stud easily. That left the 5. Two of them came out with a vicegrip. One broke beyond hope. Tried an EZ out and broke that in the head. That head went to the shop. The last two I left and had the marina use acetylene, which worked nicely.

 

[MaddyDean]

Hi All

Thanks again for all y'all help. RonDDS, Sorry you had all that trouble.

Here is the status. Port engine in completed--Found it relatively easy: Bolts came right out and the Exhaust Gasket was already pre-notched to slip over the two end bolts.

While I was there, I changed all my cooling hoses back to the Power Steering Cooler

The challenges I had--all my fault, were:

1. Putting the first exhaust manifold on, I forgot to put two bottom plugs in and the Drain fitting.
   1. I had to get down below to get them in
2. Taking the second exhaust riser off: I forgot to disconnect the cooling hose.
3. I did not buy the Exhaust Bellows so I had to run to two different West Marines to pick up the four I needed.
4. I wish I would have purchased the Exhaust Manifold drain fittings. They were pretty bad and filled with rust but I get them cleaned very well

Other then that, so far, all went well--thanks again for the advice.

Lastly, The Torque--30-pounds does not seem like a lot but i stayed in those limits.

 

[Jimmy Buoy]

Another member did have a tip for installing. From what I recall, he cut the heads off two long bolts (creating studs) and threaded them in two spots by hand, placed the gasket over the "studs", then set the exhaust manifold over the studs. After this, simply start the stock bolts in the spots not occupied by "studs", then remove the "studs" and replace with stock bolts.

This way the gasket would not be altered.

 

[rondds]

I had made some studs from threaded rod I had laying around. Problem for me was they were too long to get the second manifold on once the opposite engine had the manifold on. Stupid engines are so darn close together. Luckily I had borrowed some shorter studs from a friend and was able to get it into position. Difficult to do as a one man job unless you can sit along side the engine.

 

[MaddyDean]

Another member did have a tip for installing. From what I recall, he cut the heads off two long bolts (creating studs) and threaded them in two spots by hand, placed the gasket over the "studs", then set the exhaust manifold over the studs. After this, simply start the stock bolts in the spots not occupied by "studs", then remove the "studs" and replace with stock bolts.

This way the gasket would not be altered.

That is freaking brilliant--oh the wasted time. Bringing the sawz-all with me today.

Just got back from the boat--the cutting the bolt method saved at least an hour maybe more.

 

[MaddyDean]

Hi All

Thanks for all y'all help. I fired up the engines over the weekend and it was a noticeable difference on the way the temperatures were read. Got up to temp (170) and in the past, never went below--just kept raising. Over the weekend, as mentioned, it got up to temp then would go down about 5 degrees, go back up to temp and repeat.

I am assuming that is the thermostat opening and closing but in either case, at least it goes down.

Thank you all for your help--the best advice was cutting the heads off the long bolts--that saved hours of work.