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Scheduled maintenance replacements vs

So, I’ve been trying to research on the internet and on this forum. I apologize if this is a duplicate thread.

What I am trying to figure out is, what items should be included in the maintenance replacement as you are getting higher up in miles, and what items do you just wait on breaking to replace? For instance, do you let a water pump that’s been trucking on over 120k just keep going, or do you do preventative replacement? What should fall under preventative replacement? Rack and pinion? Struts? Head gasket?

I only know as much as I’ve learned from car talk, so I apologize that I don’t know very much about cars :wink:

Most major components fail due to the lack of maintenance.

These include anything that have a fluid involved.

Engine, transmission, brakes, power steering, cooling system.

Neglect these fluids and eventually the component will fail.

Now, I’m not saying even if you service these systems there won’t be a failure. But doing so helps to prevent these failures. And also remember that, even if you service these systems, sometimes there’s an inherent problem with the component right from the OEM. So even if you do things right, the component might fail.

As far as something like struts etc…

These are non-serviceable components.

So you use them until they wear out.


That is a big question fraught with controversy!

Unless the failure of a component causes REALLY bad things that are hard to catch before damage occurs, like a timing belt, I’d add them to maintenance. Water pumps, if driven off the timing belt get done right then, too. If I am servicing a difficult area on a high miles car I’d replace everything that will likely fail, while I’m in there IF the car looks to go a many more miles. I have rebuilt front suspensions to restore the ride and feel once the car has lots of miles. Do it all at once, align it once, happy trails!

Agree with @tester though, LACK of maintenance causes more failures than anything else. We neglect higher mileage cars because we just don’t wanna spend any more time and money on it. That causes it to fail major components. The minor stuff, you can just let wear out, for the most part.


The reason I am asking is I’m looking to purchase a 2007 4Runner with around 150k. The maintenance report is pretty impeccable (taken to the dealer every 3 months for oil changes, and they hit all the big mileage maintenances as well), but I noted that the water pumped hadn’t been changed. Could it have been that it was done personally by the owner, maybe, but based on the car’s service record, I kinda doubt it. But it got me wondering, if it is the original water pump, would I just let it keep working until it didn’t? And then what other things in a car should be replaced at certain intervals and what things should be left alone? Needless to say, I’m nervous about buying a high mileage car, but the maintenance on this was incredible so now I’m a bit torn. I’m diligent with regular upkeep, but I wasn’t sure about the longer term items in a car

I had no clue but I knew the right place to go and ask :slight_smile:

Edit: it’s a limited 2007 4Runner V6 4WD with 150k. I believe it’s on a timing chain so water pump wouldn’t get replaced with that since it theoretically never has to be changed?

I replace all belts and hoses, as well as the water pump and thermostat every 10 years or 100,000 miles, and upon purchasing a used vehicle with no proof that these parts were already replaced. I only buy vehicles with a non-interference engine, so I include the timing belt in the 10 year/100,000 mile interval. If you have an interference engine, which uses a rubber timing belt, then you should replace it much sooner than I do.

And of course, you should change your oil and coolant at a reasonable interval. I change the oil every 12 months or 4,000 miles, and change the coolant every 4 years. Don’t forget to check your oil frequently (at least every two weeks) and check that you haven’t lost any coolant, and it still looks good every month.

I would not replace struts/shocks, tires, or brake pads/shoes/rotors based solely on time or mileage. These things should be replaced when they wear out.

If the vehicle has impeccable records, then all you can do is have a pre-purchase inspection performed by an independent mechanic.

And if they can’t find any component that’s leaking, they’re not going to recommend replacement.


I’d pass on replacing the water pump. It’ll generally leak and / or make noise once the bearings in the pump fail. It shouldn’t be an item that would leave you stranded or do immediate damage when it fails. You can check to see if you notice any play in the pulley on the water pump. If not, I’d leave it alone.

I recently purchased a 2005 Sierra with 137k miles. No service history other than a sticker on the windshield indicating when the next oil change was recommended. I’ve changed the engine oil, gear oil, and transfer case oil. I plan on changing the coolant, trans fluid, and possibly brake fluid as soon as I find time. I also changed the front brake pads and rotors. They weren’t totally worn out, but I think they were the originals. I need to do the rear brake shoes, although they’ve got a little life left. I don’t plan on changing the belts or hoses, as I don’t drive the truck really long distances, but it isn’t a bad idea to change those.

Basically, I recommend changing fluids and wear items (brake shoes, belts, hoses, filters). Most anything else, I wouldn’t change unless it was showing signs of needing replacement.

While I strongly agree with @Tester and @Mustang generally I do try to consider coincidental failures and coincidentally convenient replacements. I would never replace a timing chain without replacing the water pump and all the hoses and belts that must be removed due to convenience, likewise rear main seals should be replaced when the transmission is removed for any reason and plug wires should be replaced with new plugs. And when an engine has overheated for any reason I replace the thermostat and when replacing CV axles the transmission seals should be replaced. Of course there are hundreds more similar situations.

With many years servicing fleet vehicles it became evident that the average driver operating any popular vehicle that is well maintained and avoids collision damage can expect well over 200,000 miles of relatively trouble free service. Most unexpected problems will show up first as an annoying dash light or seemingly insignificant noise or smell or minor driveability issue but if quickly investigated and corrected a break down can be avoided.

Many fleet vehicles that my shop maintained exceeded 250,000 miles, quite a few 300,000 miles and several 400,000 miles with the original engines and transmissions and never required towing for a break down.

I forgot plugs and wires as a wear item, reading Rod’s post reminded me.

Agree with what he stated about changing items when access was easy. For example, when the water pump does fail, I’d change the belts and hoses at that point for sure.

When servicing fleet vehicles, would you follow the owner’s manual maintenance schedule for that particular vehicle or did you have a corporate schedule you followed that was different?

So this is getting good! I’m starting to get the terms down, sort of.

Wear items include anything involving fluids, rubber, plastic, or wires which for the most part would present itself with an indication of some sort ahead of time. I guess brakes would fall in that category as well.

Anything more mechanical tends to be more of a replace when broken (or at least replace when service inspection finds some issue with a particular piece).

Maybe I got that rightish?

As a casual consumer, not a hobbyist of anything involving cars, the best I can do is just monitor fluid levels, follow the owner manual maintenance schedule (since it’s around 150k I would just roll it over like 100k is 0 miles?), and keep my senses sharp for detecting anything amiss?

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That’s how I kept my 97 Accord on the road for 220,000 miles.


Sounds pretty much like how I see it. Your owners manual should have a maintenance schedule outlining when to change fluids, air filter, plugs, etc. Most here will tell you to change transmission fluid and filter sooner than the manual might tell you.

In my case, I didn’t have service records. So I changed / will change everything the manual recommended at or before 100k miles. Which will be plugs, air filter, and pretty much all the fluids.

Other than some timing belts, what are some other items, that if they fail, could cause major harm to other components? Aside from like, a wheel falling off :stuck_out_tongue:

Does a timing chain cause catastrophe if it breaks? How do you know if and when to replace a chain?

That makes sense. Following the owners manual seemed like a good place to start. Thought maybe there was an extra credit maintenance schedule to hopefully ensure the vehicle stays on the road for as long as possible.

Timing chains aren’t really replaced until they start making noise or give some indication that the chain is stretched. Although, if one were to break, you’d have the same damage as if a timing belt broke. Chains don’t usually break, though. I’ve never heard of anyone replacing one as preventive maintenance. I think if you follow the “severe service” maintenance plan in the owners manual, you’ll be way ahead of what most people do.

Both my vehicles I purchased new or nearly new, and now one is 26 and the other is 46 years old.

Here’s what I do as routine preventive maintenance

  • fluids renewed or topped off as required,
  • basic tune ups for the ignition system
  • lube chassis, suspension, steering, and drive shaft u-joints
  • visual inspection of everything under the car when doing an oil change, particularly the cv boots

I’ve never replaced any part as a routine maintenance item, just replace stuff when it breaks or is showing symptoms. I have an accessory belt that’s squealing on my Corolla now for example, will be replaced at the next oil change.

Referring to my lack of knowledge about vehicles, I wouldn’t know what to look at when looking under the hood. Other than rust. Does this look acceptable for an 11 year old vehicle? Hoping to get some pictures of underneath soon.

With so many makes and models of cars and trucks to deal with from the various fleets I set up calendar schedules based on all the various usage criteria of vehicles that for the most part were similar to the manufacturer’s recommendations. The largest fleet, 140+ vehicles, was managed by an ASE master mechanic who seemed to see the logic in my methods and only rarely altered my recommendations for particular vehicles. The smaller fleets of 10 to 40 vehicles were managed by the company owners who left everything up to me and as long as there were no problems they just paid the bills remained out of the picture apparently happy that there were no break downs or complaints from the employees who drove the vehicles.Several vehicles were accumulating up to 8,000 between scheduled oil changes while some werern’t accumulating even 5,000 in the same period but that never resulted in any noticeable failures. I guess the overall basis for maintenance was keeping things manageable for myself and the customers while making an effort toward meeting factory recommendations.

FWIW, some of the seemingly insignificant procedures that are conveniently taken care of when the vehicles is in the shop for whatever reason can often mean the difference in an unexpected breakdown and another month of trouble free service. Thoroughly inspecting and gravity bleeding brakes, cleaning battery posts and cable ends, lubricating non serviceable suspension and steering components, lubricating door hinges and latches and even clutch and brake pedal linkage, etc can in time save a great deal of expensive trouble.

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Your under the hood view indicates that the vehicle was thoroughly detailed to well. If you remove the oil fill cap and closely inspect for sludge on the cap and down in the cylinder head you might find indications that the engine was not well maintained. With a mirror inspect the water pump shaft behind and below the pulley for accumulated yellowish residue from a failing pump. Closely inspect all CV axle boots to ensure they are intact. Remove the wheels and closely inspect the rotors and pads for thickness and indications of prior wear on the rotors that was ignored when new pads were installed.

excuse me. I obviously mistakenly show this post as a reply to @George_San_Jose1 when it is meant for @LewisCBall_143203
All in all the 4 Runners do seem to be excellent vehicles for first and subsequent owners. Good luck.

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