Exhaust got hot at some point!

[68ragtop]

Tearing into the 2008 RXPx I picked this weekend. Upon removing the SC I found the Exhaust temp sensor had melted & was laying on the hull. Also the air intake tube was melted some to the water box. Not sure if the cooling system was plugged at some point, or it was run too long on the trailer without a hose?

I would think the ski would trip a code if it don't see a rise in temp? There were no codes with a short startup on the trailer. (all I have been able to do so far) I will flush out the cooling lines to make sure they are not abstracted as I can see some sand inside the water inlet hose, just inside the (currently removed) pump. Can this be done on a 4-tec without the engine running, or do I have to have to have it running to prevent water from back washing or spraying into the engine?

HHhmmmmmmm

 

[LouDoo]

I think I should just come up there and take that ski off your hands. I'll give you what you paid.

Lou

 

[68ragtop]

I think I should just come up there and take that ski off your hands. I'll give you what you paid.

Lou

Lol, thanks for your help, I think?? My wife would probably encourage that offer Im thinking.
But, it would have to be in a few boxes. Its all apart already.

I can never let new toys sit. Im very OCD with new projects.

 

[Dennis]

Also make sure the three small holes in the stainless "J" pipe are not clogged. These holes are towards the end of the pipe that fits down inside the water box and approx. 1/8 inch in diameter.

 

[68ragtop]

Also make sure the three small holes in the stainless "J" pipe are not clogged. These holes are towards the end of the pipe that fits down inside the water box and approx. 1/8 inch in diameter.

Hi Dennis, I don't see that part. The pipe that extends into the box, doesn't appear to have to have one.
The rest of the pipes are clear. Just some sand at the pump & inlet hose.

I have a feeling this may have happened a while back, but Im not sure. The boot around the box is melted in a few places too. Not bad, but evidence that it was pretty hot at some point.

It bothers me that the Exhaust sensor was laying in the hull. If the MPEM thinks the exhaust is inside hull temperature, I would imagine it allowed the fuel mixture to run pretty lean.

 

[skewba98z28]

The 08 and up ski's don't have a j-pipe. You need to start 4 strokes before you turn the water on technically. With that said when the engine stops all the valves are closed so water couldn't enter the cylinders. Its still not a good idea though. Flush the cooling system and I would also back flush the intercooler with some coil cleaner and water. You wouldn't believe all the nasty that will come out of it. My buddies and I have a tub with a bilge pump in it what we flush intercoolers with. We just remove the in and out hose from the intercooler and flush it separate from the rest of the ski. When you get it all back together I would get a Groco strainer and install it on the open loop water in hose coming from the jet pump. I find all kinds of nasty things in mine that you wouldn't want going through the intercooler. I'm going to assume you are going to rebuild the charger or at least I hope you are. Good luck with it!! That ski is a beast!

 

[68ragtop]

Thanks for the input. I currently have most things apart to inspect everything. IC is out, pump, etc. My boresccope has a 36" neck & I slid it down the water inlet from the pump, lots of sand laying in the bottom of the hose that feeds the frond of the exhaust manifold. Not sure if there would have been enough pressure from the pump to push that out or not? My plan now is to remove the hoses & flush them out manually. I will flush out the IC as well. I am really not sure if the debris I am seeing now caused the overheat recently, or if it happened some time ago & the sand is typical for a ski thats not back flushed. If I had to bet I would say this ski has not been back flushed at all in recent years. I hope that there is no freeze damage as I know the ski sat outside over the winter & I see no trace of storage antifreeze.

The biggest thing is my curiosity of why it got hot. Ran on the trailer without the hose too long? Got plugged up & overheated? Maybe when I get it to the dealer for the supercharger timer reset they can tell me? Not sure how long these hold codes, or if a hot EGT sensor would even create a long term code?

If it did happen a while back & the PO kept driving it, I am still curious what happens as the mpem reads 80 degrees on the EGT nonstop. I would assume a raising temperature would increase the A/F mixture to try & cool it back down, so maybe it ran lean since? Lots of question I'll probably never know. I bought the ski at a very good price, knowing I was taking some risks, so its all good. But I don't expect to find the real answer from the PO.

 

[68ragtop]

I pulled all the hoses tonight I flushed them out. a little sand in the main inlet line, but not much. The intercooler was very full. Not restricted, but a lot of sand. To be honest, I don't think all the sand could be removed unless you remove the intercooler from the ski. I had to fill it with water & keep tipping it & dumping. It took at least 30 minutes or so. Part of the problem is the sand gets across the cores & settles the tank in the front of the intercooler. Not saying it would really cause a restriction in there, but there sure was enough of it.

As far as the water injection to the exhaust, there are three holes in the head pipe that spray water into the muffler, the water jackets in the manifold are sealed & don't flow anything into exhaust side. So its only those three holes that take care of any injected water. Nice to know that during a flush, water is not very likely to get back into the engine unless the muffler fills up first. Not that I would ever do that without running the engine, but still nice to know if the water ran for a bit, it wouldn't hurt anything.

 

[skewba98z28]

I'd say that plugged up intercooler had a lot to do with the heat issue. That is why I put a Groco on mine because that eliminates the risk. As far as leaning out I would say it would have ran like total ass if it did. Should have been pinging like crazy. If you did a compression check and its good the motor isn't hurt. Take care of the maintenance and have fun with it. :thumbsup:

 

[68ragtop]

The IC didn't seem restricted at all, but the plumbing of it appears to be independent of the exhaust cooling plumbing. Another thing I found was the restriction washer at the pump was flawed. This must have happened from the factory because the pump had never been out before & you can see an impression from where the seal was.

Does anyone know if the EGT sensor if just to warn the driver the exhaust is getting hot, or does it serve a function with the air/fuel mixture? I haven't read through much of the service manual on this ski yet, I should probably spend a few hours & do that soon.

compression was good (136-139) with a weak battery. Piston crowns looked smooth, so that part is encouraging. I am really starting to think this overheat happened when the PO ran it on the trailer too long without a cooling hose. I found a few videos on youboob of guys revving their engines on the trailer & triggering an exhaust temp alert.

Here's a picture of the pump & its failed restrictor install. Not sure how much that reduced pressure, but from the marks on the pump housing, its evident it didn't seal correctly.

(sorry its blurry, camera focused on the bench, not the pump)