Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 03-11-2014, 21:32   #1
Registered User
 
TacomaSailor's Avatar

Join Date: Nov 2012
Location: Burnt Store Marina, SW Florida
Boat: Caliber 40
Posts: 1,148
Yanmar 4JH2E exhaust problem - weak bolt holes

Our Yanmar 4JH2E is 20-years old and has 2,900 hours on it. The engine has worked flawlessly except for needing a coolant pump. We have owned the boat and engine since new.

I replaced the heat exchanger bundle as a warranty item in 1997 because Yanmar assembled a bunch of them incorrectly. No other work has been done on the exhaust system.

Last week we noticed a minor exhaust leak was putting exhaust in the engine room and later in the main cabin. Went back to the dock.

We then could see that there was a ” gap on one corner of the mating surface between the heat exchanger and the mixing elbow. Exhaust was leaking out of three of the four sides.

With more close examination, after removing three raw water hoses that blocked the view, we discovered that the bolts holding the mixing elbow / heat exchanger together had serious problems.

- One bolt was completely missing
- One bolt was backed out way
- One bolt was finger loose
- One bolt was still locked tight at 40 foot pounds

The Yanmar Factory Rebuild Manual (purchased in 1995) and the online Yanmar parts manual show that there should be four studs threaded into the heat exchanger. There should then be NUTS holding the mixing elbow flange to the flat face on the heater exchanger exhaust outlet.

Our engine had four (actually three because one is missing and I can not find in in the pan under the engine) BOLTS, which were very damaged. The 12mm head on one bolt was rusted and almost round. The other two bolt heads were clean and clearly marked with a number 7 but no other grade or class markings. The threads on all three bolts were almost completely filled with “material” and my thread cleaners and gauges were of no use picking the material out of the threads.

I was able to thread a new 8mm .125 pitch nut onto one bolt and it did clean some of the threads but the material was in effect, welded to the threads.

The local Yanmar dealer sold me four new 8mmx20mm bolts that were marked 8.8 and JH. They had a 13mm head rather than the 12mm on the original.

I have to lie on top of the Yanmar and look over the back of the engine to see and work on the bolt holes. There is not quite enough room for me to get two really good hands onto the bolts and holes.

I tried to thread the new bolts into the old holes but they did not turn easily and seemed likely to cross thread. I carefully cleaned the holes with a new 8mm .125 tap. I have tapped a lot of holes and have a pretty good feel for the work.

The tap took a lot of in-and-out work and gentle encouragement but eventually I was able to get a clean hole down to 35mm depth. The new bolts threaded in neatly and smoothly and spun down to the bottom as they would in a new hole.

When I mounted the mixing elbow to the heat exchanger I was able to easily turn all four bolts down to where they begin to compress the split washer. Two of the bolts, (the one that was missing the bolt and the one that was backed way out), turned down tightly and “bit” as I would expect.

The bottom two bolts turned down with a socket to about 5 foot pounds but then just slowly turn, as if in thick mush, and never really bite or take a set. The lowest setting on my torque wrench is 10 foot-pounds and neither bolt will make the wrench break or click.

I repeated the process with a 30 mm and 35 mm bolt to see if I could get the bolts into deeper and better material. The longer bolts will not set either.

I believe the heat exchanger is aluminum but am not sure.

There is plenty of material around the two weak holes to drill a bigger hole and use a threaded insert of some kind (Full-Torque or timeset ?) but I am not sure if that is the right thing to do. My big concern is that I have no way to ensure I drill a perfectly straight hold for the insert.

I cannot find anything about the torque that should be applied to good new bolts. The one bolt that was still set when I removed the originals was about 40-foot pounds.

There is no load on the flange – just the exhaust pressure and the heating/cooling due to the exhaust gas.

I know the right thing to do is remove the heat exchanger and take the heat exchanger to a machine shop and have them put in slightly larger holes and threads.

Are there any easier or less drastic possible solutions?

With no real shear or pull on the bolts would epoxy work?
__________________

__________________
TacomaSailor is offline   Reply With Quote
Old 03-11-2014, 21:52   #2
Registered User
 
deblen's Avatar

Join Date: Oct 2014
Location: Grand Manan,N.B.,Canada N44.40 W66.50
Boat: Mascot 28 pilothouse motorsailer 28ft
Posts: 1,403
Images: 1
Re: Yanmar 4JH2E exhaust problem - weak bolt holes

I believe you shouldn't count on epoxy type repairs,due to heat/expansion/contraction. Try a 5/16"-18 NC tap.It is a hair larger than 8mm.Then you can convert to 5/16 NC cap screws(bolts). I think 18-20 ft-lbs would be sufficient for 5/16 or 8 mm. You are at the point where the "proper" step is to remove unit for repair,which will result in using thread insert or drilling to 10mm (3/8 approx),so this is worth a try IMHO. I have used this method (on other things)before & it worked for me. / Len
__________________

__________________
deblen is offline   Reply With Quote
Old 03-11-2014, 22:48   #3
Senior Cruiser
 
delmarrey's Avatar

Cruisers Forum Supporter

Join Date: Mar 2003
Location: Now in Blaine, WA
Boat: Modified Choate 40
Posts: 10,702
Images: 122
Re: Yanmar 4JH2E exhaust problem - weak bolt holes

Actually 5/16 is .003" smaller then 8 mm.
The insert idea sounds best to me. There is a insert called keensert. You would have to drill a larger hole, if there's room and tap it. Most likely 1/2", but I haven't researched it. 5/16 & 8 mm are practically the same, just a slight tread pitch difference.
The keenserts can be purchased through granger or Mc Master. They might even have metric if you want yo go that route.

If not enough room for the keensert then a helicoil might work if the drilled hole is all metal. But this can all be a real pain laying on ones belly.

Thread-Locking Inserts | MSCDirect.com

I've installed lots of theses in my 45 years as a machinist. I prefer them over the helicoils but sometimes you don't have a choice.

.
Attached Images
 
__________________
Faithful are the Wounds of a Friend, but the Kisses of the Enemy are Deceitful! ........
A nation of sheep breeds a government of wolves!

Unprepared boaters, end up as floatsum!.......
delmarrey is offline   Reply With Quote
Old 04-11-2014, 03:52   #4
Registered User

Join Date: Mar 2009
Location: Australia, Central Coast.
Boat: Boden 36 Triple chine long keel steel, named Nekeyah
Posts: 777
Re: Yanmar 4JH2E exhaust problem - weak bolt holes

I would think a helicoil would be OK and pretty simple to fit.
To drill a straight hole, using a drill press,put two holes in a bit of say 1" mild steel bar, spaced at the same centres as on your exhaust elbow. Bolt the bar in place through one hole and the other should give you a nice square guide. If you then drill one end of the bar to take the helicoil tap you can use it as a guide for tapping as well.
If the two necessary inserts go in OK it probably would not be a bad idea to do the other two while you are at it.
Use stainless bolts, with loctite.
Don't you hate people who make engines hard to get at! A 90 degree adaptor to your battery drill might make it easier.

Regards,
Richard.
__________________
boden36 is offline   Reply With Quote
Old 04-11-2014, 04:07   #5
Zai
Registered User

Join Date: Mar 2011
Location: Athens
Boat: 2011 Bavaria 36 Cruiser
Posts: 144
Re: Yanmar 4JH2E exhaust problem - weak bolt holes

sounds like the it has been leaking for a long time and being that the exchanger is made of some type of aluminium alloy, the holes have subsequently been very much corroded.
IMO your assement about the right thing to do is correct, with the exception of I would use thread inserts instead.
Your hesitation is most likely based on the amount of extra work involved in the task. My advice is to bite the bullet and think about how well the engine has served you already.

As a side note, if it was me (and I realize it isn't) I would consider to buy a new Yanmar and replace the old one to have the piece of mind. Old engine, whats next type of thinking.

__________________
Zai is offline   Reply With Quote
Old 04-11-2014, 05:50   #6
Moderator
 
a64pilot's Avatar

Cruisers Forum Supporter

Join Date: Oct 2013
Location: Albany Ga.
Boat: Island Packet 38
Posts: 17,062
Re: Yanmar 4JH2E exhaust problem - weak bolt holes

Absolutely unquestionably an insert of your choice, I grew up with helicoils, but admit there is better out there, and locktite them in place (red) and go back with studs, not bolts.
__________________
a64pilot is offline   Reply With Quote
Old 04-11-2014, 06:46   #7
Registered User
 
deblen's Avatar

Join Date: Oct 2014
Location: Grand Manan,N.B.,Canada N44.40 W66.50
Boat: Mascot 28 pilothouse motorsailer 28ft
Posts: 1,403
Images: 1
Re: Yanmar 4JH2E exhaust problem - weak bolt holes

You are correct delmarry re 8mm vs 5/16. I suggest 3/8 NC instead.
OP was looking for a reliable "patch",to avoid removing unit & has limited space to work. I agree the proper thing is to remove unit & use inserts,but IMHO,I think he can get by using 3/8,& no harm done to unit,since it will have to be drilled at least 3/8 to install insert?
__________________
deblen is offline   Reply With Quote
Old 04-11-2014, 07:44   #8
Moderator
 
a64pilot's Avatar

Cruisers Forum Supporter

Join Date: Oct 2013
Location: Albany Ga.
Boat: Island Packet 38
Posts: 17,062
Re: Yanmar 4JH2E exhaust problem - weak bolt holes

If you go to 3/8", at least use studs and loctite them in with red (stud and bearing mount) loctite.
Myself I wouldn't put SAE hardware on a metric piece of equipment except as a temporary repair
__________________
a64pilot is offline   Reply With Quote
Old 04-11-2014, 08:00   #9
Senior Cruiser
 
delmarrey's Avatar

Cruisers Forum Supporter

Join Date: Mar 2003
Location: Now in Blaine, WA
Boat: Modified Choate 40
Posts: 10,702
Images: 122
Re: Yanmar 4JH2E exhaust problem - weak bolt holes

Loctite on an exhaust manifold?

Heating loctite is how one releases the bond!

The idea of using a 1" block as a drill guide works pretty good! I did the same thing when I replaced my stanchion bases. You just have to keep clearing the chips.
And I think replacing the whole motor is a bit extreme. 3900 hours is barely half life on a diesel. Maybe the whole exhaust, or even removing this one and doing a more precise job. Might even find more wrong with it once removed. Check out this thread>>> Yanmar Exhaust Manifold / Heat Exchanger Corrosion
__________________
Faithful are the Wounds of a Friend, but the Kisses of the Enemy are Deceitful! ........
A nation of sheep breeds a government of wolves!

Unprepared boaters, end up as floatsum!.......
delmarrey is offline   Reply With Quote
Old 04-11-2014, 08:03   #10
Moderator
 
HappyMdRSailor's Avatar

Cruisers Forum Supporter

Join Date: May 2008
Location: North Mississippi
Boat: 48 Wauquiez Pilot Saloon-C22 Chrysler Sunpiper- 19 Potter-Preparing to cruise w/my girl
Posts: 5,980
Re: Yanmar 4JH2E exhaust problem - weak bolt holes

Del has it goin' on... You need to insert this one...

McMaster link for inserts

McMaster-Carr
__________________
In the harsh marine environment, something is always in need of repair...

Mai Tai's fix everything...
HappyMdRSailor is offline   Reply With Quote
Old 04-11-2014, 08:10   #11
Senior Cruiser
 
DeepFrz's Avatar

Cruisers Forum Supporter

Join Date: Mar 2006
Location: Winnipeg
Boat: None at this time
Posts: 7,930
Re: Yanmar 4JH2E exhaust problem - weak bolt holes

Quote:
Myself I wouldn't put SAE hardware on a metric piece of equipment except as a temporary repair
+1. Mixing hardware types is very confusing.
__________________
The Blue Dot Campaign. This Changes Everything.
DeepFrz is offline   Reply With Quote
Old 04-11-2014, 08:59   #12
Registered User
 
Cadence's Avatar

Join Date: Dec 2008
Location: SC
Boat: None,build the one shown of glass, had many from 6' to 48'.
Posts: 6,063
Re: Yanmar 4JH2E exhaust problem - weak bolt holes

For what it may be worth. I would use a Helicoil as a very last resort.
__________________
Cadence is offline   Reply With Quote
Old 04-11-2014, 09:05   #13
Moderator
 
a64pilot's Avatar

Cruisers Forum Supporter

Join Date: Oct 2013
Location: Albany Ga.
Boat: Island Packet 38
Posts: 17,062
Re: Yanmar 4JH2E exhaust problem - weak bolt holes

Quote:
Originally Posted by delmarrey View Post
Loctite on an exhaust manifold?

Heating loctite is how one releases the bond!
Your exactly right, but how hot do these things get? There is nowhere I can't put my hand on and leave it there on my old 4JHE exhaust, is that un-common?
__________________
a64pilot is offline   Reply With Quote
Old 04-11-2014, 09:46   #14
Registered User
 
Terra Nova's Avatar

Join Date: Apr 2007
Location: Marina del Rey, California
Boat: Freya 39 cutter- Terra Nova
Posts: 3,651
Re: Yanmar 4JH2E exhaust problem - weak bolt holes

The casting is likely too rotten for inserts. In which case you must replace the heat exchanger.
__________________
1st rule of yachting: When a collision is unavoidable, aim for something cheap.
"whatever spare parts you bring, you'll never need"--goboatingnow
"Id rather drown than have computers take over my life."--d design
Terra Nova is offline   Reply With Quote
Old 04-11-2014, 23:29   #15
Registered User
 
TacomaSailor's Avatar

Join Date: Nov 2012
Location: Burnt Store Marina, SW Florida
Boat: Caliber 40
Posts: 1,148
Re: Yanmar 4JH2E exhaust problem - weak bolt holes

I want to thank all of you who replied and helped me understand that I had to do the right thing. And that right thing turned out to be quite easy!

After hearing from all the knowledgeable folks here - I decided to remove the heat exchanger ( HE ) and do a proper repair job.

It took less than 90-minutes to remove the alternator, all the raw water hoses, and mounting bolts or studs. Then discovered that the heat exchanger was too wide to slide off the two studs because it hit the port side of the engine room. It actually hit the two 00 cables that run from the battery switch to the starter and Link 2000 resistor that measures current. I removed the cables and was then able to remove the HE.

Took it to the dock and cleaned it and then tried to remove the bolts that hold the caps on the exchanger bundle. One of the bolts came loose easily the other not so easy. I used Liquid Wrench and a good impact wrench but no luck.

About then Chris, my professional boat mechanic and bicycle buddy, wandered by to talk and have a beer. He had just finished working on a similar HE and said we should take it to his shop.

Propane torch to loosen the stuck bolt
Drilled out the four holes with a 8.5mm (21/64) drill
Tapped new 10mm .150 threads
Put in 10mm studs that reduce to 8 mm 0.125 on the the outside (automotive exhaust studs)
Mounted mixing elbow on studs and tightened the 8mm bolts

Now the remaining problems:
- heat exchanger bundle is corroded into the exchanger housing (Chris says muriatic acid will free it up)
- HE housing around the forward bundle where the O-ring seats into a groove in the housing is badly corroded away. So much material is missing that the O-ring was protruding from the side of the cap (Chris knows a welder that builds up these exchangers all the time)
- need to bead or abrasive blast the HE and repaint it because the paint is blistered and bubbling all over
- Starter and solenoid are a rusty mess (Chris says a shop on Shelter Island sells re-built Yanmar starters for $136 + my old one)
- port lower section of Yanmar block is a rusty mess and I am not sure what to do
- need to replace three more raw water hoses and a 25" long raw water copper tube
- alternator is also a little corroded and it may need some attention

The good news is that the interior of the heat exchanger was almost perfect (except at the flange where there was some erosion) and the mixing elbow was very clean and free of any deposits. The mixing elbow and HE mating faces were clean and true.

Maybe another week will find the Yanmar running again
__________________

__________________
TacomaSailor is offline   Reply With Quote
Reply

Tags
exhaust, yanmar

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Yanmar 4jh2e Impeller Problem journey1 Engines and Propulsion Systems 8 12-08-2011 17:35
Outboard Rudder, Gudgeon Bolt Holes Repair endoftheroad Construction, Maintenance & Refit 8 01-02-2011 04:08
Filling Bolt Holes sandycohen Construction, Maintenance & Refit 6 23-12-2009 19:26
Yanmar 2GM20 F Exhaust Riser bolt Torque specs ronsunni Engines and Propulsion Systems 1 08-10-2009 12:48
hand cranking a 52hp yanmar 4JH2E rebel heart Engines and Propulsion Systems 10 15-11-2007 17:52



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 18:06.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.