Front Engine Renewal Project

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Front Engine Renewal Project


Post by Roady »

This project plan is an attempt to cover all those things that should be done when you dive into the timing belt replacement on a new-2-U bike. The bike in the pics is my '81 GL1100 but most of this applies to all years.

In this project, you will:
  • Drain Oil and Coolant
  • Remove Seat
  • Remove Shelter
  • Remove Radiator
  • Test/Replace Water Pump
  • Replace Neutral Switch ('82-'83 only)
  • Test/Replace Radiator Fan Motor
  • Test/Replace Fan and Temp Switches
  • Replace Thermostat
  • Replace Radiator Hoses and Cap
  • Evaluate/Replace Head Gaskets
  • Replace Timing Belts
I did two go-rounds of the "Remove Radiator, etc." cycle, and it occurred to me that this experience might benefit others. If you've "been-there, done-that" then please review this and help to make it a complete list. The input of the more experienced and august members of this board could be invaluable to our new members. Please contribute your helpful hints, links to tutorials and advice.

Front Engine Renewal Project
  • Front always refers to the FRONT of the bike.
    Left and Right as if you are sitting on the bike.
First, a little tour via some Honda schematics. When ordering parts or asking for help you should refer to parts by number and name. The names and numbers in this writeup refer to these drawings. Before taking on a fix I like to look up these drawings at to familiarize myself with the terrain. Other sources for the same drawings are Western Honda and (they give good phone at 800-828-5498).

Don't let that one make you nervous. You probably won't have to take all that stuff apart.

#8 on the left side of the engine gets removed to pull the radiator. Then you can inspect the water pump. If it's good all else on that side stays put.

Remove the Radiator

Put the bike on a solid surface and up on the centerstand. If you run the back wheel up onto a 1' long piece of 2"x8" it will be a lot easier to pop it up on that stand.

Organize. Have small containers ready for bolts and nuts. Whenever possible, return fasteners to the hole they came out of. That way it's there when you are putting things back together. Keep bolts together for each phase of the disassembly. For example, these all go into cup #1: oil drain bolt; water drain bolt; water pump cap bolts; radiator bolts, cap nuts and washers. The shelter and seat bolts all go into cup #2.

Drain the oil by removing the bolt under the filter with your 17mm wrench. Loosen the bolt (14mm wrench, aftermarket is 17mm) in the center of the filter and let it drain. Remove the filter housing, discard the filter and stash the housing someplace safe. Drain the water by removing the bolt (14mm). It will likely spray forcefully so be prepared to catch the fluid.

The voice of experience spoke to me on 8 Dec. 2008:
bigjnsa wrote:... when you say, "will likely spray forcefully" when draining the coolant, you should change that to read, "expect Niagra Falls when you open the radiator cap after removing the bolt." ;)
Please dispose of old fluids properly. It's the least we can do for our furry friends oldies (like WF)

Remove the seat. There are Allen head bolts on the right and left. Bolts, washers, adjuster into cup #2. Then slide it back and lift the front.

Remove the shelter. Two 10mm bolts at the front, one each side on the bottom. Two 12mm bolts at the rear, on top. Cup #2, got the idea? Stand on the right side of the bike and slightly lift the shelter. Then pull up on the left side to twist it off. Keep it parallel with the bike and jiggle a little here and there. It's got a sweet spot that it likes to come off of. You will not need to force it.

Push the handlebars fully to the left.

Remove the radiator cap and overflow tube from the radiator riser.

Remove the left horn. There are two electrical plugs and 2 - 10mm bolts. Store safely (how 'bout next to the oil filter cover?).

Loosen the lower clamp on the upper radiator hose (#7, right under #5 in the radiator drawing), it's 10mm. Get the hose off of its connection to the thermostat housing.

Disconnect the fan's electrical connection. It's way up by the top of the top hose. This may have to wait until you've got the radiator loose.

Get down on the ground on the left side and remove the two bolts (8mm) from the Water Pump Cap (#8 ) and pull the cap away from the water pump cover. Leave the hose connected.

Remove the right-lower bolt (10mm) that holds the radiator to the frame. Bolt and washer into cup #1 (enuf with the organize?). Loosen the left-lower bolt until you can turn it with your fingers but don't remove it.

Remove the right-upper cap nut and washer. Remove the left-upper cap nut while supporting the radiator with your third hand. If you didn't get the fan connector unclicked, tilt the top of the radiator forward, reach in from the front and get it now.

Support the radiator and remove the lower-left bolt. The radiator is free. Almost. Now it gets tricky. Keep supporting the radiator, get yourself around to the right side of the bike and push the handlebars fully to the right. (NOTE: I put the top-right cap nut back on for this.) You should now be able to finagle the radiator down to free the filler tube from its niche in the frame and then work the radiator free.

Look at all that purty stuff behind there!

Now would be a good time to have the radiator boiled out. Call around to find a shop and get some quotes. You'll need to take everything off of it before delivering it to them. Or, you can try it yourself by flushing scalding hot distilled water through it.

Test/Replace Water Pump

Wiggle and Jiggle the water pump. Move the impeller (just inside #7) around with your fingers. All GL1100s originally came with a Bakelite (plastic) impeller. Replacements will likely have a metal impeller. Reach in the hole and push, pull, wiggle and turn the impeller. It should not turn more than about 1/16". It should not move noticeably either left, right, up or down. (Also see Randakk's post about a Bad Bearing.) The weep hole on the bottom of the housing should be clear and open. Push a wire up there to check. Have a read through Octane's Water Pump Leak, Why & How for more details.

If your pump is solid and the weep hole is clean, you may now skip ahead to Replace Thermostat.

If the pump moves around and is sloppy it needs to be replaced. Here's where we'll be going.

Some have had success with rebuilding these pumps. But Honda's recommendation (and mine) is to replace it with an OEM pump. It ain't easy to get to and can be replaced for about $125. To rebuild you'd need the two bearing ($20 or so each) and a mechanical seal ($50) so you're almost at the cost of a new pump. Order the pump and a Water Pump Seal Kit. If the pump feels good but the weep hole is full of rusty crud, you should at least pull the transmission cover and disassemble, inspect, clean and replace all the seals.

If you do decide to rebuild the pump, first read Octane's Water Pump Rebuild tutorial.

Remove the water pump transmission cover. Get a piece of cardboard to store the transmission cover bolts. Draw a rough sketch of the trans. housing on it and as you remove a bolt, jab it into its place on the drawing. There are 3 different lengths. You'll thank me later for the cardboard tip (like I thank Octane every time I do it).

NOTE: For GL1000 owners. Your bolts are Phillips Head and may be difficult to remove. Placerville had success with Howard Halasz's Bingo Method as described in Randakk's Tech Tip, Water Pump R&R Details on his web site. Placerville's extract from that page can be found in this post.

Remove the 4 hex head bolts (8mm) from the water pump cover. The two long ones are trans. cover bolts. Get the cover off. Good luck. Do not jam a screwdriver in there to pry it off or you'll ruin the gasket surface. The Haynes manual says to tap lightly with a rubber hammer. Mine required a bit more force and ended up being taken off when I got the transmission cover on the bench.

Remove the 9 hex head bolts (8mm) from around the trans. cover. I had the best luck with my 1/4" drive socket set. Remove the cover. Again, no prying. Tap around with a rubber or leather hammer. Take care to find the 3 dowel pins and note their locations if they fall free.

Remove the three bolts (10mm) that hold the pump in the trans. cover. Discard the 3 crush washers. Lightly tap and press the pump out toward the front.

Have a cold one and have a little chuckle at all those that skipped ahead and don't get this treat!

Clean up all of the parts real good. Remove all traces of the old gaskets and discard all o-rings.

Make real sure that all the water and oil journals/passages are clear.

See, I done a pretty good job. Hey, these parts are hidden and don't need much polish in my book.

Survey your new parts and water pump seal kit with new cover gaskets.

Install the pump using new big o-rings and 3 new aluminum crush washers. Torque the bolts to 6 to 9 ft. lb.

Replace Neutral Switch ('82 and '83)

My '81 does not have this, of course. It's #6 in the transmission cover drawing.
Sagebrush wrote:IF it's an '82 or newer 1100, replace the neutral switch. You're going to be staring it in the face when you remove the transmission cover to get to the water pump.
Sodbuster wrote:The neutral switch is unique to '82 and '83 models. The position of the switch is critical.

Notice the position of the pin in the switch in relation to the bolts. Also, the short end of the pin points to the 2 o'clock position. This is important for ease of reassembly of the transmission cover and also to ensure the switch is in the correct position for proper operation.

Replace Water Pump Seals

Please read the water pump/trans cover section in 40 Build by Pierce. You'll find lots of tips and pics that will help with this part of the project.

Clean up the front mating surface on the block. Again, check and clear all water and oil journals and passages.

Remove the old water pump seal and install the new one.

All but one of the o-rings (it's about 1") in the kit have a home on the '80-'81 models. Make sure that you get them all in and well seated. There's a new one for the water pump cap #8, too. I like to apply a bit of grease to them so they'll stick in place. Put the 3 alignment dowels into their holes and hang the new trans. cover gasket on the front of the engine. Install the trans. cover with its 9 - 8mm bolts. Not too tight, yet.

Put the water pump cover gasket in place over the two dowels on the trans. cover. Install the pump cover using its two short and two (extra) long bolts (all 8mm).

Tighten the 13 - 8mm bolts evenly and in a criss-cross pattern. Round and round gradually until they all snug up evenly. I couldn't get my torque wrench to most of them so I guesstimated on the 6 to 9 ft. lb. of pressure.

Replace Thermostat

These can be tested but just pick up a new one and replace it. NAPA gets $7 for theirs. The dribble hole ("jiggle pin") goes up, at the 12 o'clock position. A new o-ring for the cover would be nice, I didn't have one and the old one looks good so it went back in.
  • NAPA #101
    STANT #13868
    Carquest #32438
    Honda Auto #19300BP2024
180 degree type with a 52mm mounting flange and bypass relief port.

Test/Repair/Replace Radiator Fan Motor

Hotwire the leads from your fan motor to the battery. If it snaps right on and runs smoothly then you're good to go. If nothing happens you'll need a replacement or you might try what I did. I disassembled the fan motor and cleaned it up. The brushes were rusted and corroded into their races and weren't contacting the commutator very well. The commutator had a black stripe at the contact point. I freed the brushes and polished up the copper surface of the commutator. Then cleaned all the surfaces using silicone spray, steel wool and elbow grease. A little dielectric grease in the race and it runs like a champ.

Test/Replace Radiator Fan Switch and Temperature Gauge Sender

The fan switch on these Wings is notorious for taking a digger. If yours is wired with a toggle switch for the fan, you need to fix this switch. The instructions in the Haynes manual are about as good as it gets.

Also, read my Fan Thermo Switch thread for more details. For excellent instructions on using a non-OEM switch (meaning, 'cheap'), see AzCycle's Alternative Fan Thermo Switch thread in the How-To forum.

Replace Radiator Hoses

Buy one NAPA #7733 radiator hose and cut it to make both the upper and lower replacements. Use the old hoses to select the best segments of the new hose. There's only a little bit of waste so cut carefully

Replace Radiator Cap

Just replace it.

NAPA/Belkamp #703-1445 or STANT #10229.

Evaluate the Head Gaskets

This part is entirely subjective. It's torn down this far and now you have to make a decision. You can't really look at the head gaskets without ruining them. But you do have evidence of how hot the engine has been running and for how long it's been running hot. Evaluate the condition of the radiator hoses, fan and switch, thermostat and the radiator itself.

Do replace the head gaskets if the pump was trashed. If the bike ran hot for too long then it will likely blow a head gasket in the near future. Even if you've fixed the cooling system, those gaskets are tired. It's not much further to go once you have all the above done. And it'll cost you under $100 to finish it up right.

Parts to order from the Cylinder Head and 'Stat drawings:
  • 2 x Cyl Head Gaskets (#6), 12251-MG9-306, 35.35 ea. = 70.70
    2 x Oil Control Orifice O-rings (#18) (6.5x1.5), 91305-371-003, 1.20 ea. = 2.40
    2 x O-rings for the same orifice (#19) (4.1x1.5), 91308-371-003, 2.39 ea. = 4.78
    2 x Water Joint Gaskets (#7, Thermostat drawing), 19429-371-306, 3.15 ea. = 6.30 *see Note
    4 x Water Joint O-rings (#14, 'Stat) (21.9x2.3), 91301-MB6-003, 1.04 ea. = 4.16
    4 x Exhaust Pipe Crush Gaskets, 18291-286-306, 3.55 ea. = 14.20
    Ground Shipping = 9.00
Total Price = $111.54 *Aug. '08* -- Your parts should arrive within 4 days.

*Note: 8/31/09 Unless you're some kind of purist or have a leak there, don't take off the Water Joints (#6 in the Thermostat drawing) at the top of the heads. Those two little sticky gaskets (#7 in that pic) are expensive and a real pain to get off. Just leave em bolted down. After the head's 7 bolts are out you can work the tubes off at the o-rings.

Other parts to consider when you order are the two rubber Valve Cover Gaskets and 8 seals/washers for the valve cover bolts.

You and the manuals are on your own for this one. It goes exactly as outlined in the Haynes Manual. If you don't have a printed Official Honda Manual, Haynes Owners' Workshop Manual or at least a Clymer's by now ... well ... you ought to get one.

Replace Timing Belts

This is the most important reason that you're in here with the radiator off and grease all over yourself. Your horizontally opposed boxer engine is what's known as an interference engine. If a belt breaks, the valves are going to interfere with the movement of the pistons. Something will give. Believe me, it will. And that is usually the valves, if you're lucky. It could also involve broken pistons and other things that are just too horrible to talk about on this family-friendly forum. And you'll probably end up looking for a replacement motor.

Do yourself and the bike the biggest favor and replace the belts now. They're cheap and very easy to get to while you're down here.

Octane's super Timing Belts, Removal and Installation How-To is absolutely the best in the business.

Finishing Up

Put it all back together like it came apart. Do not install the shelter and seat.

Refill the oil. Buy 4 or 5 gallons of Distilled Water, a bottle of Prestone Flush and a gallon of 50/50 Non-Silicate Coolant. Some swear by Honda only coolant but when I was quoted almost $20 for it I started shopping around. Peak 50/50 at Wal-Mart goes for about $8 and is non-silicate.
  1. Pour the flush into the radiator and top it off with distilled water.
  2. Run until hot (fan should come on).
  3. Let it cool down. Drain it.
  4. Fill with distilled water.
  5. Run until hot.
  6. Let it cool down. Drain it.
  7. Repeat 4, 5 & 6 until the water is coming out pure.
  8. Fill with non-silicate 50/50 coolant/distilled water.
  9. Install the shelter and seat.
All Done? Great! Go for a Ride!

Intellectual Property Notice:
Feel free to LINK to this material. However, the content published here is the property of Steve "Roady" Mate, and is protected under United States and international copyright laws. The photographs, text and other content may not be copied, reproduced, republished, distributed, stored, or manipulated in any manner without the express written permission of Steve Mate.
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Last edited by Roady on Thu Dec 24, 2009 10:54 pm, edited 22 times in total.
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Post by octane »

Absolutely brilliant Steve !
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Post by Sagebrush »

Great job! I hope somebody stickys this.
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Post by octane »

Sagebrush wrote:Great job! I hope somebody stickys this.
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Post by gllimb »

perfect i need that :shock: :shock: :shock:
gl1000 1978
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One extra O ring???


Post by wingd »

Roady, great info. The ? I have is about the statement made about the O rings......(All but one of the o-rings (it's about 1") in the kit have a home. Make sure that you get them all in and well seated. There's a new one for the water pump cap #8, too. I like to apply a bit of grease to them so they'll stick in place. Put the 3 alignment dowels into their holes and hang the new trans. cover gasket on the front of the engine. Install the trans. cover with its 9 - 8mm bolts. Not too tight, yet.) My ? is were does that extra O ring go??????? I have my 81 GL1100's front engine cover off and I'm ready to get r back together and I ran across this O ring in the gasket kit O ring assortment. Never saw it on the tear down....I don't think!!
1981 GL1100 Std 130+k miles and counting!
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Post by Roady »

That extra O-Ring is for the 83-84 Neutral Switch. I could not find it in any of the drawings that I have even tho' the switch is shown on the Transmission Cover and Water Pump drawing.

Maybe someone with 83-84 manuals could look it up.

It certainly does not belong anywhere on the 81, guaranteed.
Last edited by Roady on Tue Jan 13, 2009 11:00 pm, edited 2 times in total.
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One extra O ring???


Post by wingd »

Roady, thanks for the info. I'll just toss in my assorment of extra parts.
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Post by 1CrazyMoFo »

Very nice write up and maybe the spring I'll fix that leaky cover for the 3rd time and it won't leak!!

Mistakes I made:

First time: no gasket, hey prema-tex will work.....Not, although it didn't leak, it would also not shift. This cover works as a bump stop for some transmission stuff.

Second time: Spent $20 bucks for the gasket. Lightly greased it and installed. Leaks like a pig, but shifts great! Due to the Phillips head screws getting tired, I opted for Allen heads. Which leads me to believe they are over tightened and maybe warped the cover.

Third time: Will have to happen soon as it is making me crazy and in the garage it's getting dangerous to walk even walk by the Wing. I'm think of using spay on gasket adhesive and a different cover (of course checking it for straightness first) and really choking up on the ratchet, may even just use a small Allen wrench...I really like the Allen's.

I may be a slow learner, but I have learned to make sure it shifts after installing the cover!!! Good luck! :lol:

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Post by cjflyer »

What a great write up!!! Thank you so much for your efforts to help other folks! Books are a must but write ups from those that have been there are priceless! :o :o :o :o :o :o
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Just finished the project!


Post by DutchPurrpl »

Hey, just letting you know I finished a combination of this project and several more "while the wheels were off". Thanks to all who have contributed to this wealth of great information. I figure I saved over $1000 by doing the front engine work, the timing belts, and the drive spline while the rims were in for new Dunlop Elite IIIs. Total cost for all (minus tires) was about $140. Of course, that's in addition to the great satisfaction and bonding with the machine. Thanks again for all your help.
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Post by Roady »

Thanks, Dutch.

It's nice of you to comment, there's my paycheck for the month. ;)


Post by DutchPurrpl »

You're welcome, Roady. I've made a donation as well to keep the info flowing.
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Re: Front Engine Renewal Project, GL1100


Post by rbridges »

Can someone who knows for sure please tell me where to buy all the gaskets/seals for the water pump replacement job? Is there a genuine Honda kit, or do I have to know all the separate part numbers? Or is there an aftermarket kit which is up to snuff? I need to know all the part numbers etc if I can't buy a good kit that has it all. Thanks for your help. 1981 1100i. Randy.
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Re: Front Engine Renewal Project, GL1100


Post by Whiskerfish »

Go to the top of this Forum and click the button for Home. That will take you to our front page. On the lower Left side (you may need to scroll down a bit) are our 3 sponsors. Click on Crescent Moon Cycles. Crescent Moon carries a complete water pump kit that has all the seals ready to go. It DOES NOT include the pump.
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and a whole garage full of possibilities!!

Psst. oh and by the way CHANGE YOUR BELTS!!!!
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