Coolant Bypass Hose - a ticking time bomb ??

[ajkalian]

I was planning on doing a bit of cooling system maintenance before winter set in. Like change the top/bottom radiator hose, the heater hose, and the thermostat, which is the original. Flush everything out, add some new coolant and be set for the winter.

So I was putting a list together of all of the parts I would need and noticed something called a Coolant Bypass Hose. Hmm, never heard of that, and I had never seen it either. After a bit of research I found it. It's located under the intake manifold. You can't see it no matter how hard you try. And I know for a fact that it's the original one, since I've never changed it.

To get to it, I'd have to remove the Throttle Body, the EGR stuff, the Plenum, the injector rack, the intake manifold just to get to a $10.00 hose. But wait, it gets better. Take a look at this picture, and you will notice there are two Knock Sensors. So I figure it might be a good idea to replace them while I'm in there. I looked up the part number for my car 89615-12040 and they list for $184.00 EACH. Checking eBay I found some for *only* $75.00 each.


http://www.toyotanation.com/photos/s...cat/500/page/1


Here's the Knock Sensor. When I asked the parts guy why the KNock Sensors were so expensive, he mumbled something like, "the have very rare elements in them". Yea right, like Horshitium, I suppose.

Amazon

Amazon

And I would have to buy a gasket set for the intake manifold, and the plenum. Amazon shows it for $58.00. So I'm wondering if I should just kick the can down the road, forget about the Coolant Bypass Hose and the hassle of removing the entire top of the motor to get to it.

I found another thread on re-locating the knock sensors, and I might consider it especially if I go through the trouble to replace the coolant hose and then two weeks later the knock sensors go bad. That would just be my luck.

Any thoughts on which way to proceed would be appreciated.


.

[Mister_Perkins]

Originally Posted by ajkalian

I was planning on doing a bit of cooling system maintenance before winter set in. Like change the top/bottom radiator hose, the heater hose, and the thermostat, which is the original. Flush everything out, add some new coolant and be set for the winter.

So I was putting a list together of all of the parts I would need and noticed something called a Coolant Bypass Hose. Hmm, never heard of that, and I had never seen it either. After a bit of research I found it. It's located under the intake manifold. You can't see it no matter how hard you try. And I know for a fact that it's the original one, since I've never changed it.

To get to it, I'd have to remove the Throttle Body, the EGR stuff, the Plenum, the injector rack, the intake manifold just to get to a $10.00 hose. But wait, it gets better. Take a look at this picture, and you will notice there are two Knock Sensors. So I figure it might be a good idea to replace them while I'm in there. I looked up the part number for my car 89615-12040 and they list for $184.00 EACH. Checking eBay I found some for *only* $75.00 each.


http://www.toyotanation.com/photos/s...cat/500/page/1


Here's the Knock Sensor. When I asked the parts guy why the KNock Sensors were so expensive, he mumbled something like, "the have very rare elements in them". Yea right, like Horshitium, I suppose.

http://www.amazon.com/Toyota-4Runner-Avalon-Corolla-8961512040/dp/B003DSCXKQ


And I would have to buy a gasket set for the intake manifold, and the plenum. Amazon shows it for $58.00. So I'm wondering if I should just kick the can down the road, forget about the Coolant Bypass Hose and the hassle of removing the entire top of the motor to get to it.

I found another thread on re-locating the knock sensors, and I might consider it especially if I go through the trouble to replace the coolant hose and then two weeks later the knock sensors go bad. That would just be my luck.

Any thoughts on which way to proceed would be appreciated.


.

Rule of thumb is if it has visible cracks or wear to replace it. The only thing I've replaced on my Gen 3 camrys are the radiators that rotted away. The coolant hoses are all original . Just something to think about.

If you DO end up replacing the coolant bypass hose, please please please unbolt it evenly in sequence. If you unbolt it unevenly, you risk warping the manifold and will have to surface the manifold. (Its aluminum so it warps easily).

The knock sensors are very expensive ... Their job is to detect engine knock and sends a voltage signal to the ecm.. the ecm uses that signal to control the timing. Inside the knock sensor is a piezoelectric element. piezoelectric elements generate voltage when pressure or a vibration is applied to them. The motor makers put them in certain spots, because they work best at their location. Moving them to a different location I would not recommend doing.

They do go bad, but you would more than likely see a head gasket go bad before you see a knock sensor go bad.

Hope that helps