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View Full Version : exhaust manifold drain plug removal? what size allen key are they?


pbgbottle
10-25-2011, 09:32 PM
quick question on the exhaust manifolds how do you remove the drain plugs .what kind of tool do you use. and in my case they look like they have never been removed .i am thinking i might have to pull the manifolds and use some heat is this a doable idea?
can i put heat to these things, i have never had them off yet and don't know what they look like on the inside .
i am the new owner of this old boat. ,i am also new to inboards . so i am learning as i go .

thanks jake

mikeg205
10-25-2011, 09:38 PM
quick question on the exhaust manifolds how do you remove the drain plugs .what kind of tool do you use. and in my case they look like they have never been removed .i am thinking i might have to pull the manifolds and use some heat is this a doable idea?
can i put heat to these things, i have never had them off yet and don't know what they look like on the inside .
i am the new owner of this old boat. ,i am also new to inboards . so i am learning as i go .

thanks jake

allen key? what year...do you have picture?

Cloaked
10-25-2011, 10:07 PM
quick question on the exhaust manifolds how do you remove the drain plugs .what kind of tool do you use. and in my case they look like they have never been removed .i am thinking i might have to pull the manifolds and use some heat is this a doable idea?
can i put heat to these things, i have never had them off yet and don't know what they look like on the inside .
i am the new owner of this old boat. ,i am also new to inboards . so i am learning as i go .

thanks jake Jake,
I use a 1/2" drive socket ratchet. Works perfectly. I am referring to the exhaust risers and not the exhaust manifold. I presume you are asking about these two drain plugs (1 each side).

Not much on the inside per se. Just an empty riser compartment. Remove as gently as possible, as they should back right out. The trick to these plugs is to replace the plugs in the spring with new ones using Never-Seez and pipe thread tape. Tighten ONLY to the point of hand tight (even if that is still loose) and leaking water. Leaking is what you want for the moment. Then tighten ONLY until the threaded connection stops leaking water (once you are on the lake or start the engine otherwise). STOP there. Not one more twist, turn, or snug for good luck. The manifild threads often will strip out easily from over tightening, even the slightest. I also try to use new plugs each season (at ~$2.00 each), and the Never-Seez will make removal much easier next time. I use Never-Seez on all threaded connections as well as hose connections. It keeps the hoses from sticking to the connection and makes it easier for the next time.

Next thing to consider are the exhaust hoses. If they are old, replace them. They can collapse internally and obstruct the flow of water, creating issues with cooling. Use soft wall hose from skidim. When doing this it is much easier to remove the exhaust riser to replace the new hose. If you choose to do that, order 8 new bolts and two new gaskets to reinstall the risers. Again, Never-Seez...:)

.

mikeg205
10-25-2011, 10:12 PM
why would you remove those bolts to drain when the brass blug is lower than those allen bolts - for winterizing? There's hose lube you can get at autozone that is a designed for hoses... big believer in anit-seize as well....

Cloaked
10-25-2011, 10:18 PM
why would you remove those bolts to drain when the brass blug is lower than those allen bolts - for winterizing? There's hose lube you can get at autozone that is a designed for hoses... big believer in anit-seize as well....The drain plugs are right under the exhaust hose(s) at the lowest point of the riser. Those are the ones to remove. Bolts on top are for the riser connection to the exhaust manifild. No need to remove unless you're changing exhaust hoses, etc.

pbgbottle
10-25-2011, 10:48 PM
i just took a pic for you guys .mine is hexagon shape ,wow! the manifold looks rusty in the pic . the manifolds don't look that bad at all .must of been the flash .:eek: gonna have to get some paint on them . i have not tryed to remove them .but they look like they will be seized in there .i have a buddy bringing me over a socket tommorrow to see if we can give them a twist otherwise they will be staying in for now.

what do you guys think .will they come out

Lumbergh
10-26-2011, 02:44 AM
I had one that was so seized I ended up pulling riser and manifold and taking to shop to get it out.

Thankfully its easy and fairly cheap to remove / replace. I am using all new hardware to be safe and give me piece of mind (new gasket + bolts for both riser and manifold).

Its hard for me to let things alone that I know are messed up and can be taken care of with a little time and effort.

I read that about a quart of water will come out of the manifold plug. On removing mine, that seems like an accurate figure. Water sitting in a cast iron manifold can't be good and will definately rust.

I agree that new brass plugs every season might be a good idea. They are less than $5 each.

east tx skier
10-26-2011, 10:15 AM
Don't just paint over the rust. Leave it be.

Cloaked
10-26-2011, 05:13 PM
Upon looking at your picture, do as another poster said and take it to a machine shop, however they will not guarantee any results.

Try soaking the threads with PB Blaster maybe...... then remove the plug(s) if they loosen up....

If you're OK with leaving well enough alone, leave it alone. There is maybe 1 - 2 quarts of water at most (in each). Optionally, open the chamber through removal of the riser (not my first choice) or remove the forward hose at the thermostat housing and pour a 50/50 solution of anti-freeze down into the hose and on into the riser chamber. Drain the remainder of the block (two plugs) and the J-tube plug. Pull the hose from the bottom of the tranny cooler to drain that, and it's a done deal.

Or fill the entire engine with the 50/50 solution until it comes out the exhaust. Another done deal.

.

Cloaked
10-26-2011, 06:21 PM
.....what do you guys think .will they come out :D No... :D

That is a nasty looking situation.... I'd let that b!tch sit until you start loosing sleep over it...

pbgbottle
10-26-2011, 08:07 PM
i think i am going to just run some antifreeze throught it and then shut it down and most likely drain the engine and leave it be .i found some SIERRA Antifreeze-Coolant premium quality propylene glycol for an engine not RV stuff, hopefully this stuff won't kill my dog .

i may put some heat to them and see what happens .i'll post back if i ever get them out.
so if they do come out without stripping , can i replace them with brass plugs ?

thanks for the feedback guys .

cheers Jake

Cloaked
10-26-2011, 08:18 PM
i think i am going to just run some antifreeze throught it and then shut it down and most likely drain the engine and leave it be .i found some SIERRA Antifreeze-Coolant premium quality propylene glycol for an engine not RV stuff, hopefully this stuff won't kill my dog .

i may put some heat to them and see what happens .i'll post back if i ever get them out.
so if they do come out without stripping , can i replace them with brass plugs ?

thanks for the feedback guys .

cheers JakeBrass should fit just fine.

Stabilize your gasoline while running. Put some stabilizer in the tank and then allow that treated fuel to circulate through the carb. it will start much nicer in the spring. RV stuff is just fine and less expensive.

pbgbottle
10-26-2011, 08:24 PM
i was reading on the bottle of the RV stuff and it said it doesn't like to mix with water ,you must completely drain all water from your tanks before using it .so i was a little nervous to use it ?

Dave Osk
10-26-2011, 08:50 PM
I had the exact same problem this fall with the PS190 I bought this summer. My manifolds had the 1/2 inch square female plugs mentioned earlier in this thread. They were all ready rounded out so I removed the manifolds this fall, cut a short piece of 1/2 x 1/2 bar stock and spot welded them into the pipe plugs. While they were hot I was able to break them loose with a breaker bar. Heat from welding did the trick. I chased the threads and will install new plugs this spring. I plan on using the Mercrueser plastic plugs with the drain valves. Had really good luck with them in he past.

Cloaked
10-26-2011, 08:50 PM
Either way... Dog will never know the difference... :D :D

Fuel treatment will be your friend on the 4160 carb. Prevents gumming...

boater8987
10-26-2011, 10:18 PM
I had the same problem on my Prostar 190 when I first bought it. I removed manifolds and risers. Used a small oxy-acetalene rig and heated them up and unscrewed them because they will strip the centers out if stuck or it breaks off a peace of the plug. You can heat the plugs first then heat around them. Also good time to take risers off and clean and inspect both riser and manifolds. Clean sand,wire brush and repaint exterior and install these drains with plastic hose on them long enough to stick through drain plug hole so no rusty water drains into bilge. Also replace motor drains with easy drains and hose too. http://www.skidim.com/prodinfo.asp?number=MCM000 Then put back together with new gaskets and new bolts.

boater8987
10-26-2011, 10:20 PM
I had the same problem on my Prostar 190 when I first bought it. I removed manifolds and risers. Used a small oxy-acetalene rig and heated them up and unscrewed them because they will strip the centers out if stuck or it breaks off a peace of the plug. You can heat the plugs first then heat around them. Also good time to take risers off and clean and inspect both riser and manifolds. Clean sand,wire brush and repaint exterior and install these drains with plastic hose on them long enough to stick through drain plug hole so no rusty water drains into bilge. Also replace motor drains with easy drains and hose too. http://www.skidim.com/prodinfo.asp?number=MCM000 Then put back together with new gaskets and new bolts.

ricford
10-26-2011, 10:38 PM
I remove mine every year and I don't think I've ever had more than a drop or two of water come out of them.

Dino Don
10-26-2011, 10:42 PM
On my Indmar 351 the block on the left side is easy to drain--it's the other side with starter that's a pain--I just run RV antif. thur it till it comes out the exhaust.

d2jp
10-27-2011, 08:40 AM
On my Indmar 351 the block on the left side is easy to drain--it's the other side with starter that's a pain--I just run RV antif. thur it till it comes out the exhaust.

My block drain on the starter side is well forward of the starter - towards the front of the engine. The left drain is on the rear, the right on the front-side of the block, just behind alternator.

Lumbergh
10-27-2011, 10:32 AM
My block drain on the starter side is well forward of the starter - towards the front of the engine. The left drain is on the rear, the right on the front-side of the block, just behind alternator.

The forward drain on the right side (behind drivers seat) is also the shower tap, at least it is on mine.

I added QD couplings to my shower (and heater lines as well) to make quick work of these tasks.

thatsmrmastercraft
10-27-2011, 12:23 PM
i think i am going to just run some antifreeze throught it and then shut it down and most likely drain the engine and leave it be .i found some SIERRA Antifreeze-Coolant premium quality propylene glycol for an engine not RV stuff, hopefully this stuff won't kill my dog .

i may put some heat to them and see what happens .i'll post back if i ever get them out.
so if they do come out without stripping , can i replace them with brass plugs ?

thanks for the feedback guys .

cheers Jake

4 or 5 gallons of the cheap RV antifreeze is the stuff to use. Search "winterization" on here and you will have tons of reading.

pbgbottle
10-30-2011, 09:56 PM
update .got them out !:D
9/16 allen head socket and a big breaker bar and a pipe wrench on the end of the plug and two of us wrenching .one of them cracked free right away the other was a quite a bit tighter . but in the end they both came out . also took each manifold bolt out one at a time and cleaned them up and put some never-sieze on them . also put two new drain cocks in the block .
do they make drain cocks for the manifold?

pics attatched . the inside of the manifold is full of crap .:(
and a small pic from the net of the drain cocks. ;) below


,,,,,,,,,,,

Table Rocker
10-30-2011, 11:22 PM
Manifold drains exist, but are easily clogged with rusty scale.

http://www.skidim.com/prodinfo.asp?number=MCM003

Kevin 89MC
10-31-2011, 10:54 AM
I have the drain kit from Skidim, installed it several years ago. They do clog once in a while. Once I got the feel for how much should drain out of them, I got comfortable leaving them in. I usually have to pull one of the four when I winterize. I had the old style clog up as well, so keep an eye on those too. I would probably get them again, but they are not maintenance free.
Good luck,
Kevin

Cloaked
10-31-2011, 09:12 PM
update .got them out !:D
9/16 allen head socket and a big breaker bar and a pipe wrench on the end of the plug and two of us wrenching .one of them cracked free right away the other was a quite a bit tighter . but in the end they both came out . also took each manifold bolt out one at a time and cleaned them up and put some never-sieze on them . also put two new drain cocks in the block .
do they make drain cocks for the manifold?

pics attatched . the inside of the manifold is full of crap .:(
and a small pic from the net of the drain cocks. ;) below


,,,,,,,,,,,Excellent. Glad you got the issue resolved. Remember what I said about putting them back in, in the spring. I have learned the hard way, more than once.


.

James L.
11-20-2011, 09:32 PM
I purchased my 1990 ProStar 190 just over a year ago. I discovered similarly corroded threads, as shown in the picture posted above by pbgbottle, in the exhaust manifold and engine block drain holes when I winterized it in the fall of 2010 so I switched to brass drain plugs for both locations. I did not have any problem getting the brass plugs out when I winterized the boat today, but I did find it difficult to thread the plugs back into the drain holes. Seems like the drain plugs wouldn’t hardly even turn a full revolution before they snugged up today, which is what I experienced when I first used the brass plugs last year as well.

Has anyone ever tried using a tap to chase the threads in those drain holes? Did it improve the situation?

James L.

mikeg205
11-20-2011, 09:48 PM
Yeah, I had the very same problem this spring after I winterized last year...so I keep those threads covered with anti-sieze....actually any good motor grease will work....now I care for those threads all winter...a little TLC goes a long way like cloaked says...no my plugs, pet ****, and knock sensor spin right in.....

Thrall
11-26-2011, 02:34 AM
If you'd have had to heat the manifold to get the plugs out, you should heat teh manifold, not the plug. The manifold will expand slightly and make it easier. Just like removing exhaust mainfold studs.
Don't put petcocks in the block drains. Use plugs. The petcocks can plug up easily with silt.sand/rust and leave water in the engine.

prostar205er
05-22-2013, 04:31 PM
Reviving this thread...

So my exhaust manifold drain plugs threads are full of rust so I can't get my plugs to go in even a quarter turn. I knew I was on borrowed time as each year when I winterized they went back in less and less (and I didn't think to replace the plugs but in hindsight, as maybe that would have helped???). I think this last summer was the end of the line as I could see there had been some leakage over the course of the season and fear this summer could be worse. So I could use some help/suggestions.

Is there something I can put in there to eat out the rust so that I can regain some of those threads? Or re-tap the threads? I've read that I shouldn't force the brass plugs in there (but since I didn't see that first I tried and ended up only stripping the threads of my brass plugs). It is mainly at the bottom of the threads where the water has rusted over time. I tried picking at it with a screwdriver and was able to remove some of it, but not enough to really get my plugs to go in. Any thoughts or suggestions would be great (short of replacing the manifolds would be even greater!).

Thanks!

Lumbergh
05-22-2013, 11:23 PM
I vote for a 3/4 NPT tap.

prostar205er
08-21-2013, 02:49 PM
The 3/4 NPT tap did the trick! (Along with a few shots of PBBlaster)