I had my timing belt replaced last Thursday (as general maintenance at 70k miles, not due to a problem.) On Saturday I noticed that I was leaking coolant. Not a lot, but I never leaked before. I’m going to call my mechanic this morning, but wanted to know if it could be related to having the belt replaced? I’m not familiar with the process. Does the radiator get disconnected and could it just be a loose clamp? Maybe a puncture somehow? Coincidence?
They are often directly related, depending on the vehicle. Many times a water pump replacement will be done at the same time as a timing belt replacement, because a new water pump is cheap, and the labor involved in replacing it is expensive, but most of that labor is already done in a timing belt replacement.
This could well be a coincidence, however. Or maybe it’s only tangentially related, like you have a hose that’s old and brittle and all the moving around from the timing belt replacement caused it to spring a leak.
As a general rule, when you replace a timing belt you ALWAYS replace the water pump. First you are already in there so the labor cost is almost nil, second they tend to require replacement due to failure and/or leaks at about the same interval.
It certainly depends on your particular make and model of car - it’s common for water pumps to be under the timing belt cover, and/or something to be removed in the process of getting to the belt. Either way, it’s one of those “As long as you’ve got it out, might as well change it” things as you’ve already done 98% or so of the labor to get to the pump.
I would say they are definitely related. The water pump is often not only located under the same cover as the timing belt, but very often the water pump is actually driven by the timing belt, being situated right between the cam and crankshaft gears.
Just got back. It is the pump. They did NOT change it out during the timing belt replacement, and now they need me to come back so they can replace it. Luckily it’s covered under warranty so there’s no charge, but it is another day without my vehicle. Thanks to everyone for the information.
A heads-up: Another new part the mechanic is supposed to install at the same time as the timing belt is the belt tensioner. And for the same reason as the water pump.
Thanks!
I cannot even imagine not changing the tensioner when doing a timing belt.
In old “timing chain” days the water pump was typically either fan or alternator belt driven.
And was reliable to go 200K and if it failed there was never a concern for it to destroy the engine at failure.
Who do we owe the Thank You to.:mad:
My first intro to the joy of the modern timing belt/chain was my 1987 Acura Legend.
Being the first year of full roll-out, each car came with a shop manual on the spare.
I flipped through scheduled maintenance and found it to be an 80K item - and cost $700.
They actually had to dis-connect the engine from just about every wire and hose, loosen its mounting bolts, connect an engine hoist and partially lift the engine out of the car to get to the damned thing.
I now drive a 4 banger Nissan truck.
Do other “modern” cars require this effort to replace a critical part? This often?
Fortunately, the trend lately has been back towards timing chains. Hopefully we’ll all look back and laugh at periodic timing belt changes someday.
And you also typically had to remove it to get to the timing chain.
Where the water pump is behind, and especially where it’s driven by, the timing belt, I routinely suggest replacing the pump as a preventive maintenance. However, though it’s a good idea to replace it at this time, there’s not a compelling reason to do so. If the pump is leaking or has roughness in its bearing, then it goes beyond being wise maintenance and is a repair situation where it would be extremely foolish not to replace it.
Likewise, I routinely suggest replacing the front crankshaft and camshaft oil seals, and likewise if they’re leaking it’s repair rather than maintenance. Same logic as the pump – the timing belt has to come off to get to them, and they’re not likely to last until the next belt replacement interval.
On some designs with known tensioner problems it’s good practice to replace the tensioner, but on most designs the tensioner, its pulley, and any idler pulley(s) commonly last until the next belt replacement interval. Of course if there is any sign of a problem (rough bearing, tensioner piston position not to spec) then it needs to be dealt with along with the belt.
Most engines of the last 10+ years (maybe 15+) have timing belt replacement intervals of 90K-105K miles, some even longer. On the great majority of designs, access is far better than on that 1987 Legend, though a few are a similar pain.
While timing chains typically have a useful service life noticeably longer than timing belts, they don’t last forever. Many will stretch and eventually jump teeth, some can break. Whether or not a broken or jumped belt or chain does further engine damage isn’t a function of its being a belt vs. a chain, but of whether it’s an interference engine or a free-running engine. Broken/jumped chains have been known to bend pushrods and/or valves.
There are comparative advantages and disadvantages to timing belts vs. timing chains. Neither is perfect, and neither is flatly “better” than the other. The fact that both are widely used in modern production reflects this.
I had (or rather my wife did) an Audi A4 V6; the timing belt on that thing was incredible, about 15 feet long. The dealer said, no problem, we can replace the belt, but not for another week. We had to drive several hours home from the city that weekend! So we got a mechanic shop to fix it, they slipped a cog while trying to change the belt; not to mention that they had the entire front end, radiator and all, taken off to do this job. At about 80km/h the motor started to “thrum” in an odd pattern, I assume because the exhaust valves weren’t closing on time.
Could be worse… in the category of “who do we thank?” I first encountered rubber timing belts with my 86 Honda Civic. At 103,000km and 5 years 4 months, the belt broke. $1200 top end job. I found out a year later it should have been replaced at 80,000 before the 100,000km / 5 year warranty ran out. Could be worse, apparently taht dealer’s mechanic was showing a customer how easily a Honda motor turned; he turned the crankshaft by hand with the timing belt disconnected for a motor on the bench. After that, the motor needed a new top end job.
I just love when **Gary T ** jumps in all authoritative and shit.
He and Tamerlane are the two posters I absolutely 100% trust with their facts, figures and reasoning.
Thank you both!
</fanboy nerdgasm>
That is lamentable stupidity for someone employed as a professional mechanic. But it does show how easily valves can be bent.