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Do it myself Honda water pump replacement.

Updated on January 10, 2011

How do I know if the water pump is failing?

I can't stop myself from doing automotive repairs completely. After 35 years of running auto shops, every now and then I need to get a spanner dirty myself on jobs I don't trust an auto shop to do.

Water pumps are one of those jobs I will not trust to anyone else. You will see in the photo of the Nissan water pump why I don't trust others to replace my water pump.

Water pump failure destroys many motors, even more than broken radiator hoses or leaking radiators, because you need to replace your water pump BEFORE it stops functioning!

There are three pretty reliable indicators of pending water pump failure, two of them are 100% accurate.

  1. Look for even one drop of coolant that has dripped from under the front of your car overnight. Not a big puddle, that is likely to be a different problem, just a drip or two. This is likely to be coming from the relief hole in the front of the water pump, and by looking up, you may see a drip on the bottom of the water pump. If so it is dead.
  2. You may also see a powdery white coating on the front of the water pump that is corrosion caused by the coolant getting past the water pump bearing seal. 100% fatal.
  3. You may hear a tiny grinding sound that changes with engine revs, and I know that sound well on any car. It is distinctive in it's metal grinding sound and means that the water pump bearing seal has been broken for some time, allowing the bearing to become damaged by the particles in the coolant. If you remove any other driven components such as the alternator or power steering pump belt, you will be more certain if it is the water pump making that noise you hear. As the pump gets closer to complete collapse the noise will become louder and sound even more like metal being ground against metal which is what is going on inside the pump bearing.

Having to replace my Nissan utility water pump recently (it's done 235,00 klms.) I got a lift down to the spare parts shop in my son's Honda. I had phoned my parts supplier to confirm the pump was in stock, then pulled the pump off the ute to check it against the replacement to ensure proper fit.Some vehicles when new, had 2 different water pumps in the same year of manufacture, so it pays to check it against the replacement water pump to ensure it will fit your exact model number.

On the drive down to buy the Nissan water pump, I could hear that familiar water pump grinding noise that preceeds water pump failure coming from my son's little Honda, so we got a water pump for the Honda at the same time. It cost AU$80.00, a little dearer than the Nissan one and stamped with the original equipment logo. Exactly the same part that was fitted when the car was new. I have been using the same supplier for 30 years, as he really knows his business.

The Nissan pump was easy to access.

The old pump I took off  the Nissan had been fitted by someone who did not know or care. The patches of silicon says it all. I put it back with the dry gasket provided after cleaning with thinners.
The old pump I took off the Nissan had been fitted by someone who did not know or care. The patches of silicon says it all. I put it back with the dry gasket provided after cleaning with thinners.

I refuse to use cheaply made after-market moving parts as they often fail without warning, and if that happens to the water pump there is a good chance of instant overheating resulting in an engine rebuild. Never drive with a hot motor, it kills the engine internals by altering the metal and doing serious damage that will cost thousands to fix. If you turn off the motor immediately, in most cases damage will be minimal.

Always use high quality replacements for all moving parts such as water pumps, wheel bearings, tie-rod ends, idler and Pitman arms, suspension bushes, struts, links, springs, alternators, disc brake rotors, in fact any moving part. You can buy cheap replacements for body panels and other static components but even then you can expect problems with fitting them, as they are seldomm perfectly formed, and bolt holes may be off centre.

You can see in the picture that the pump was badly fitted the last time it was changed.

Typical water pump supplied with dry gasket.

There is no need to put any goo on the dry gasket, just ensure the mating surfaces are clean.
There is no need to put any goo on the dry gasket, just ensure the mating surfaces are clean.

Buying the parts.

The owner of my parts supply shop is first and foremost a good motor engineer himself and all his parts are OEM equivalent or better. His prices are often half what the dealership wants to charge me for exactly the same part from the same manufacturer with the same part number.

If you have a friend who knows a lot about cars and does his own repairs, find out where he or she buys spares. You may get lucky and find a place that has knowledgeable staff at the counter. These guys are dealing with mechanics and auto shop owners all day so prices are close to wholesale because the smartest auto shop owners will always track down parts that are highest quality at the best price.

If your referring friend knows his spare parts shops and has pointed you in the right direction you will be surprised at the level of service, product quality, and guidance freely given with the refit of the part. These guys will usually inform you of any little tricks to ensure you don't make any mistakes, as this is the level of service that the smart auto shops expect and get.

Don't bother with the McDonalds type of cheap auto parts shops. They are useless for advice, and sell bad value for money consumables of dubious quality,

You will find the cheap junk parts are only about 5 or 10% cheaper than you will buy a quality part at a shop that is more engineering focused and a major supplier to the better repair shops that have highly skilled mechanics who already know not to use rubbish parts..

Some O.E.M parts ( from the manufacturer of your vehicle or original parts) are prone to failure due to poor design and thereby need a better replacement than the original to be trouble free.

For example the original cam chain and adjuster on Renault Scenic's are not worth the work involved in fitting them. As the standard part was crap, my replacement parts guy only stocks a high quality modified cam chain tensioner with a stronger belt. Because I have an old established supplier I hardly ever need to go elsewhere no matter what make of vehicle I am working on, they have the parts I need, or can get them for me usually the same day.

Even when using the best quality water pump, things can go wrong though.

Before fitting the new Honda water pump I pulled it out of it's box and turned it slowly by hand to ensure the bearing and seal offered the right amount of resistance to being turned. A new pump will not spin, it is easy to turn but slightly stiff because of the very tight tolerance.

As I turned it I explained to my son that I always check every new part before fitting, as although the chance of getting a faulty part from my supplier was minimal, I try to avoid doing any job more than once, so don't take any risks with part or fitting.

I revolved the pump slowly and ........... found a potential problem! In one spot I could feel a slight variation in resistance so that it had this tiny tight spot in each 360 degree revolution by hand.

Years of working with fine engineering on racing motorcycles has taught me to be very suspicious of such anomalies, so I took the water pump back to the shop to exchange it.

I handed the pump to one of the spare parts salesmen and he turned the pump many times but could not detect any tight spot. The staff obviously enjoyed this challenge and passed it from one to the other each diligently trying to locate the spot and demonstrate their ability to me. No luck. They were as always, willing to do anything at all within their power to help and immediately offered me another pump. I agreed eager to get back home in time to do the repair. Then the computer had some bad news, no stock until tomorrow. So Ray, the engineer that started the business and I both examine it, and disovered that the more we revolved it, the less we could notice the problem. We decided on a few theories that would be acceptable explanations and decided to fit the pump anyway as Ray reckons it would be OK. He buys thousands of these things and has not had more than a couple of doubtful returns, so I am very confident in his knowledge.

Honda Water pump.
Honda Water pump.
The Honda air-conditioner compressor like this one sat over the top of the access point and needed to be removed.
The Honda air-conditioner compressor like this one sat over the top of the access point and needed to be removed.

This Friday we decided to replace the water pump. My 20 year old boy did most of the work with directions as to which order to proceed in.

Most water pump replacement is dead easy these days, it is getting to the pump that takes the time, and providing you ensure that the "o" ring or gasket is in place and both surfaces are clean they are easy to replace on the cylinder block or extended housing.

The Honda has an air-conditioning mounted in a caste iron housing that would support a house. Although this is fitted by Honda, it is not OEM, but fortunately with Honda's strict adherence to quality control it is strong and does not allow any vibration.

It is also bolted on very tight, so we needed quality sockets and ring spanners to undo the support bolts which we did not have at home.

The procedure is simple enough, but easy if you get the steps right. In this case it was remove the air cleaner, the inlet manifold heater tube, the pulley of the end of the water pump, loosen the rocker cover, then the cam belt cover, undo the four bolts holding the water pump on, then pull it off past the loosened cover which partly covers the water pump which is why it needs to be loosened. If you mistakenly loosen the very tight 12mm bolt in the centre of the cover, no harm done, when you re tension the bolt it will have simply allowed the cam belt tensioner to readjust itself as it would be done in service.

Even doing the job in the driveway with a few hand tools did not take more than a couple of hours, apart from some time lost in removing the air-conditioner mount with our cheaper than cheap spanners. As the Honda has rubber sections in the air conditioner compressor lines, we did not have to disconnect the hoses which meant no need to recharge the air-conditioner.

We took a fare bit more time than needed cleaning the chassis and inner fenders while we had access, replacing the odd light bulb and generally giving it some of the care it should have been getting a lot more regularly!

All in all any easy afternoon's work, and my son now knows a lot more about looking after his car.


After replacing the water pump you need to bleed the air out of the system after you partly fill it with coolant until it covers the top tank. Then squeeze and release the lower radiator hose until no more bubbles rise out of the radiator filler cap and the fluid level drops. Top up and repeat until the radiator is full and there are no more bubbles.

Run the motor with the radiator cap loosened until all the bubbles have gone, but not long enough to get the motor warm. tighten the filler cap with the radiator full but not the reserve bottle. Run the motor while watching the temperature carefully. Switch off.

Wait 20 minutes then open the radiator cap again and run the motor. If coolant pours out the top, you still have an air lock. Try squeezing the lower radiator hose again half a dozen times, watching for bubbles.

Watch the cars operating temperature for half an hour to ensure it does not suddenly overheat from air trapped in the system. Many systems will self bleed with the cap removed, others are a nightmare and heaps of care is required. That will require another hub.


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    • profile image

      bellyJacobs 5 years ago

      An engine driven Water Pump can be a very helpful tool to have around the house, farm, boat and even on the job. It can help in all sorts of tasks ranging from the not so important like draining the swimming pool to, the very important like watering crops, outing a fire and even draining a flooded home or a construction foundation.

    • earnestshub profile image

      earnestshub 7 years ago from Melbourne Australia

      I agree Ladyface, more fun to make one yourself. Air pumped out, oil comes in. Nice and simple.

    • L a d y f a c e profile image

      L a d y f a c e 7 years ago from Canada

      I think I could probably make that with things I've already got kicking around my garage. More of a challenge that way ;)

      Thanks again!

    • earnestshub profile image

      earnestshub 7 years ago from Melbourne Australia

      Hi Ladyface. It is a tall plastic container with a hand pump built in much like a garden sprayer. It has a long tube that goes down through the oil dipstick hole to the bottom of the sump to suck the old oil out. If the oil level was correct, replace with the same amount of new oil in the filler at the top.

      I sold them when I had my business and will try to find a picture of one, but it is so simple you may be able to make one. Definitely under $100 as I recall, so probably half that at the moment.

    • earnestshub profile image

      earnestshub 7 years ago from Melbourne Australia

      Thank you eddie, I have recently seen some beautiful new spanners on the market with an "elbow" in them. I gotta have a set of them for engine bolts.

      I just hate diving in to all the plastic and bolt-ons to get to the job on some late model units.

    • L a d y f a c e profile image

      L a d y f a c e 7 years ago from Canada

      The oil evac unit sounds pretty sweet. I've been searching online and can't find anything that tells me how exactly it works. Might you have some info? I didn't know that was possible!

    • eddiecarrara profile image

      Eddie Carrara 7 years ago from New Hampshire

      Nice hub earnestshub, knowing the parts guys is a big help, and it can save you big bucks. I worked at the same Honda dealer for 25 years so I know the parts department very well. Water pump jobs are getting more difficult each year and it's not something I recommend for a weekend warrior. The most difficult part of doing a timing belt on new Honda is breaking free the crankshaft pulley bolt, but with the right tools ,anything is possible. Keep up the good work

    • earnestshub profile image

      earnestshub 7 years ago from Melbourne Australia

      Thanks hardlymoving. Good that you mentioned a supplier (Rockauto) my American readers can use.

      The big boys in the industry have different names in Australia such as Autobarn and Supercheap but with the same useless counter staff and lousy stock.

      I don't know the American after-market spares shops, but thanks to your comment I will begin some research on them through a motor engineer mate in the States.

      Very useful comment.

    • earnestshub profile image

      earnestshub 7 years ago from Melbourne Australia

      Thank you Ladyface. On many cars you can put a shorter belt on and leave the air-conditioner compressor drive out of the configuration. It just depends on how the belt will clear other components because of it's layout.

      By the way pantyhose can be used as a fan belt in an emergency on some cars.

      It's great that you are doing your own maintenance. I educated my customers about their own cars when I could.

      An educated customer is the best type to deal with, as they understand the importance of preventative maintenance.

      You can buy a oil evacuation unit these days that will hand pump the old oil out of your car without spilling a drop. They can be purchased for under $100 and will pay for themselves quickly. It only takes about two minutes to do an oil change and you don't have to go under the car to remove the sump plug. I will continue to write more tutorials and am about to start making my own videos too.

    • hardlymoving profile image

      hardlymoving 7 years ago from Memphis, TN

      Good article. Over 90% of my purchases are through They are consistently cheaper than the big retail auto suppliers and have much better inventory of name brand parts manufacturers/suppliers.

      Unfortunately, the small, independently owned parts shops have been blown out of the water by the big retail chains such as Advance Auto, Auto Zone and Pep Boys. They usually don't have the part you want in stock, the people at the counter know virtually nothing about cars and are completely dependent on what's on the computer monitor to make recommendations.

    • L a d y f a c e profile image

      L a d y f a c e 7 years ago from Canada

      This is excellent! I got tired of being treated like someone who has no idea what a timing belt is by auto mechanics in my area, and started doing things myself. My ac compressor broke and because I let them work on it instead of just figuring it out myself, my air conditioning is completely broken. According to them, you can't put a different belt on to take it out of the equation until I could get it fixed. But I asked another, and they said I could. So who the heck knows? A fortune to repair.

      I recently changed my own oil. :D (not a big deal to a mechanic I know.. lol)

      I towed a friend's car (99 Accent I think) whose water pump had broken. I just have an F150 and tow straps so he was behind me, and he had a hard time steering the car. When I got there and he started it up to show me, it was SO LOUD and high pitched.

      I hope you come out with more of these tutorials! Conveniently enough for me, I have a Honda (Accord) :)