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Newbie, with my first jet boat & I think I screwed up already……

Finally got my Rogers on the water for the first time this past weekend. Everything was looking good at first, then she started overheating. Ended up pegging the temp gauge. Limped back to the dock & shut down the engine. Everything was hot including the logs & risers, & could hear the water boiling or creating steam in the block & exhaust.Even though I have logs & risers, I thought I would be a bit too clever & install a pressure relief valve. During the run the valve was leaking & I am pretty sure I had it adjusted to too low of a pressure. After getting it back on the trailer & thinking about it I am pretty sure the pressure relief valve was bleeding off enough pressure that the engine wasn't getting enough water volume from the pump, but that's just a guess. Checked the dipstick & didn't see any water in the oil, & engine ran well before I cooked it…..

[/size]The main questions I have are: Is it possible that I have fried or compromised the engine by running it that hot?  Any ideas on what to do next to determine if I caused any damage?[/color]


(454 BBC, mild flat tappet cam, rectangular port heads, compression ratio unknown, probably around 10.5:1, pump just rebuilt.)[/font]


Any advice or suggestions?[/font][/size]

Three things to do simply for piece of mind.

First,  compression test,  cheap,  quick and easy.

Pass that,  leak down test.  A little more difficult and time consuming,  but will give you a good idea of engine condition.

Pass that,  pressure test the blocks water side.

Pass that, let her buck.

GT

Thanks GT,


The compression test I could probably handle, + I've got #s from doing a comp test before this incident to compare to.
Would doing a cold test at this point be o.k. as a go-no-go indicator?


Have never done a leak down test myself, so would need expert help with that….


If you don't mind, how would one go about pressure testing the block?

If you don't mind, how would one go about pressure testing the block?

Pretty simple really.

Plug the thermostat outlets by putting the hose on both fittings Then pressurize the inlet of the water pump holes at the tee. Put 15 psi of air on it and listen.

The compression test cold would be enough information to see if it has to be pulled apart IMO.

GT

Dan'l


It's got a gate valve, probably 8 years old by now. It seemed to be working o.k.  A new ball valve would be up upgrade though?…..


G

Gate,  not ball.

Trust me here.

GT

Pretty simple really.

Plug the thermostat outlets by putting the hose on both fittings Then pressurize the inlet of the water pump holes at the tee. Put 15 psi of air on it and listen.

The compression test cold would be enough information to see if it has to be pulled apart IMO.

GT

GT,


Cool, that does sound pretty simple.
I want to hear no air leaking = good?
If air is leaking, or where the leak (sounds like it) is coming from, is going to indicate? Cracks, or blown gaskets, or??

GT,


Cool, that does sound pretty simple.
I want to hear no air leaking = good?
If air is leaking, or where the leak (sounds like it) is coming from, is going to indicate? Cracks, or blown gaskets, or??

Head gasket,  cracked head,  broken block.

She should hold 10 psi for quite a while.

GT

If its a pressure relief valve Remove and replace with a Gate valve

Dan'l

Right. I had the pressure relief valve plumbed after the gate valve. Abandoning that experiment though & eliminating the PRV…...

Head gasket,  cracked head,  broken block.

She should hold 10 psi for quite a while.

GT

GT,


Which of the three tests would you recommend doing first, compression, leak down, or pressure test?
I have some time after work today to get started on this.....


G

Compression test is the easiest and will tell you right away if you need to tear stuff down.

JMHO

GT

GT,


Thanks.
Gonna get to that tonight.  I'll post the results.....


G

GT,


O.K., did a cold compression test & a pressure test on the water side per your instructions.


Compression test: #1 -150    #2 -149
                             #3 -149    #4 -149
                             #5 -150    #6 -149
                             #7 -149    #8 -150


These numbers are similar to what I had before the overheating event. 
Plugs looked good, or at least nothing abnormal, I think. Insulators are a toasty brown, & air/fuel rings showing maybe a bit of a rich mixture.  (If there was water getting in the cylinders & burning with the fuel would they look washed out or clean?)


For the pressure test on the water side, I put around 12-15 lbs of air in the system after sealing it up.  I could hear the air as it was filling up, then listened pretty carefully around the block, logs & didn't hear any air escaping. Used a  length of 5/8" hose to listen into each spark plug port & didn't hear any air entering there.  Now, to be honest, noticing a subtle leak is probably beyond my skill level, plus a bit of ambient noise were I was doing the test (just outside my garage) might have prevented the test from being absolutely conclusive?…..


Thoughts?


G

I say make the necessary plumbing changes and run it.

Doesn't sound like you hurt anything at all.

GT

GT,


Thanks.  I have read a bunch of your posts & you are very generous with your experience & offer a lot of great advice here on SCJB, so I trust your opinion.
Gonna x-out the PRV & go back to the stock plumbing configuration, & try to dip it back in the water in the next couple weeks.


A couple more questions:  1. A few folks had mentioned changing the oil as a precaution.  Do you think that would be a good idea, or necessary? (Current oil only has about about an hour on it including tune up time out of the water.)
                                         2. Loaded question: what weight oil do you recommend?  (I know there is a lot of discussion about this, but since I am new to jet boating, I have no real frame of reference...)


Thanks again & I'll let you know how it works out.


G

Thank you for the kind words.

As for changing the oil.

Two different avenues of thought.

One,  what if something happens to contaminate the new oil?  It seems to me I would run it and ensure nothing is jacked up. Otherwise you would have wasted the oil for nothing.

Second,  I am a huge fan of an oil analysis. If the oil is clean,  let it buck.

I have been known to replace the filter and top it off,  cutting the filter apart looking for issues that may exist.


As for oil weight,  it really depends on too many factors to get into on a forum,  but honestly,  a quality 15w-40 with the proper compounds for the cam package you have is likely adequate. I actually like running straight weight oil simply because the winter rated number will never be an issue if you boat in the summer (the "w" number notes the weight of the oil at 32°F, the other number is at 212°F).

For example,  I run 50 weight Amsoil full synthetic in my garbage.

Roller cam 496 Chevy.

Flat tappet camshafts should really run a zinc fortified oil.  Anymore it's easiest to run an oil specified for diesel engines,  like Rotella or Delo.

A little research will help you in that decision.

Check out

http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=cfrm

There is a ton of great information in there,  not just the forum, there are a bunch of in depth articles worth the read.

Hope this helps.

GT

Update on the overheating issue:
Took the boat out to Elsinore today for a test run. she started overheating pretty much right away. No joy. Went right past operating temp & kept going up.  Luckily was only about 75 yards or so from the dock, so the temp was (only) about 220 by the time we got her back.  Surprisingly, other than overheating, the engine ran fine, in spite of my inadvertent attempts to kill it……..


I thought, after it overheated a couple weeks ago, that the PRV that I had plumbed in after the gate valve was the culprit. Although it may have contributed to the problem, eliminating it did not solve the issue.


Here it is in a nutshell:
-Boat overheated.
-Did compression check ( all cylinders around 150 psi)
-Pressurized block with about 10-15 psi of air & didn't hear any discernible leaks.
-Changed the filter & oil ( cut open the filter & it seemed to look normal.  Oil was somewhat dirty, not unusual, & no water except while draining, at the very end, a little swirl of milkshake, no more than a couple of ounces)
-Eliminated the PRV between the gate valve & the logs
-Took her out again today & had same overheating issue
- got her home & decided to see what kind of water flow was going through the engine & pump.  Pulled the water lines going to the risers, plugged them into a tee fitting, with a 1/2" hose going outside the hull. Ran some water through the engine & logs.
Got a nice stream of water exiting out the 1/2" hose. (ran off the garden hose with a WP regulator set to about 15 psi)
Checked for any obstructions on the pump side by running some water back thru the pump past the gate valve. Got what seemed like plenty of water exiting the pump nozzle.


Feeling like I'm ready to wave the white flag at this point.


GT, any words of advice, or suggestions?

Risers plugged with shit.

Pull the exhaust hoses and check for chunks.
Pull the 90 into the riser and check for chunks.

Check each log individually.

Does one side get hotter than the other?

GT, thanks,


I'll check those areas. Figure on pulling the logs/risers as well & running some water and air through them to see if they are clear, & check for debris.


(I did have the logs& risers polished a month or so ago. When I pulled them, it looked like they hadn't been messed with in quite a while .  Cleaned out the water passages pretty good, I thought, & removed more than a bit of corrosion.


(One thing I forgot to mention: Along with doing the compression check, etc., I replaced both exhaust hoses thinking they might have gotten damage from the first overheat. (The originals didn't look thrashed i.e. no blistering, etc.)


It seems like both sides (logs) get equally hot. I mean, everything seemed hot, even the water in the hoses going all the way back to the gate valve was hot.


The way I ran water through the engine @ home  this afternoon, seemed to indicate that water was getting through both the logs, & block.  Since the risers are where the water exits, those being plugged by debris or corrosion would cause the cooling system to be over pressured?


Just a thought:  Based on what I saw today @ Elsinore, it kind of seems the engine is getting very little, or no pressurized water from the pump bypass, just the amount that would naturally enter the cooling system from the intake & bowl being underwater.
A blockage, in the system after the pump bypass/gate valve, would probably act like that too, which seems like where you're headed with your suggestions?
Is it even possible that the pump is not providing enough pressure or volume from the bypass to adequately cool the engine, or is that just my inexperience talking?……....