SoCal Jet Boats
Tech Talk => Engine Mechanical / Electrical => Topic started by: Bullzybull on February 16, 2016, 07:32:17 PM
-
Hey guys, I have a 1978 18.5 ft Hallett mini day cruiser with a stock 460 ford and a Berkeley JC. I bought it from the original owner at the end of last year. It runs and is in overall great shape. When I got it home I noticed that not a lot of water was running out of the port side exhaust. I pulled the water lines off the snails and found what appeared to be sand and calcium in the line coming out of the bottom of the port side snail and very little sand out of the starboard side. Once replaced the water hoses I had a lot better flow out of both exhaust tubes. With everything looking good I took it for a spin at my local lake.
Once I got it out on the lake it ran great for about 25 minutes. Then all of a sudden I noticed a decrease in propulsion and my temp gauge starting to rise. I immediately backed off the throttle and headed toward the ramp. By the time I got close to the dock I had practically no propulsion and the engine had reached a temp of 225. from the time I initially noticed a problem to the time I shut it down and pulled it out was around 10 to 15 minutes. I pulled it out and went home.
After I got home I opened the hand hold and noticed a little bit of grass wrapped around the impeller shaft. Worried that the overheating blew a head gasket I checked the oil on the dip stick and found no milkshake. I also pulled all the plugs and checked for water. I found no water in any of the cylinders. I then did a compression check on all the cylinders and came up with the following:
1. 115 5. 60
2. 118 6. 80
3. 120 7. 80
4. 125 8. 50
cylinders 5-8 are all on the port side and are obviously significantly lower. What do you think would cause the entire port side to have such low compression? I was hoping to get some feedback from you guys before I tear into it. Thanks in advance!
-
Did u do a compression test cold or hot ? I would do a leak down test on cooling system . See if it holds pressure
And leak down test on cylinders . Have u recently done a valve adjustment ? Just throwing ideas out there .. Good luck
Sent from my iPhone using SoCal Jet Boats
-
Hey guys, I have a 1978 18.5 ft Hallett mini day cruiser with a stock 460 ford and a Berkeley JC. I bought it from the original owner at the end of last year. It runs and is in overall great shape. When I got it home I noticed that not a lot of water was running out of the port side exhaust. I pulled the water lines off the snails and found what appeared to be sand and calcium in the line coming out of the bottom of the port side snail and very little sand out of the starboard side. Once replaced the water hoses I had a lot better flow out of both exhaust tubes. With everything looking good I took it for a spin at my local lake.
Once I got it out on the lake it ran great for about 25 minutes. Then all of a sudden I noticed a decrease in propulsion and my temp gauge starting to rise. I immediately backed off the throttle and headed toward the ramp. By the time I got close to the dock I had practically no propulsion and the engine had reached a temp of 225. from the time I initially noticed a problem to the time I shut it down and pulled it out was around 10 to 15 minutes. I pulled it out and went home.
After I got home I opened the hand hold and noticed a little bit of grass wrapped around the impeller shaft. Worried that the overheating blew a head gasket I checked the oil on the dip stick and found no milkshake. I also pulled all the plugs and checked for water. I found no water in any of the cylinders. I then did a compression check on all the cylinders and came up with the following:
1. 115 5. 60
2. 118 6. 80
3. 120 7. 80
4. 125 8. 50
cylinders 5-8 are all on the port side and are obviously significantly lower. What do you think would cause the entire port side to have such low compression? I was hoping to get some feedback from you guys before I tear into it. Thanks in advance!
This has me going down two completely different roads.
The first road is could be a failed head gasket. It would be weird, but hey.
The second road would be valve adjustment. Reaching there two.
Stupid question of the day.
Did you have the throttles opened all the way for the test? Did you do port first? Fuel washed?
Wet it up with some oil and do it again.
GT
-
This has me going down two completely different roads.
The first road is could be a failed head gasket. It would be weird, but hey.
The second road would be valve adjustment. Reaching there two.
Stupid question of the day.
Did you have the throttles opened all the way for the test? Did you do port first? Fuel washed?
Wet it up with some oil and do it again.
GT
X2
Sent from McIntyre Park
-
I'll agree to some extent with Glenn. You measured the "good" side first. I'll disagree about oiling 'em up, that will give you a false positive. Disconnect the pump, or back it into the water, get it fired and up to temperature...you may need oil in the cylinders to make compression to get it hitting on all 8, but that will be gone after a few minutes of running. Then do another compression test. Get a charger on the battery, hold the throttle wide open, disable the ignition. The goal is to have the same cranking speed on every cylinder and no fuel to wash the cylinders down or sparks to surprise you. Running the engine will condition the cylinder walls appropriately for meaningful test results.
-
I'll agree to some extent with Glenn. You measured the "good" side first. I'll disagree about oiling 'em up, that will give you a false positive. Disconnect the pump, or back it into the water, get it fired and up to temperature...you may need oil in the cylinders to make compression to get it hitting on all 8, but that will be gone after a few minutes of running. Then do another compression test. Get a charger on the battery, hold the throttle wide open, disable the ignition. The goal is to have the same cranking speed on every cylinder and no fuel to wash the cylinders down or sparks to surprise you. Running the engine will condition the cylinder walls appropriately for meaningful test results.
My thought on a tad of oil will tell you if the head needs to come off is all.
I like your method better. I'm a little more down and dirty.
GT
-
My thought on a tad of oil will tell you if the head needs to come off is all.
I like your method better. I'm a little more down and dirty.
GT
i'm a little more lazy, and too cheap to buy head gaskets ifn I don't need 'em
-
I was thinking head gasket but wouldn't it seem weird that all 4 cylinders would be lower in comp and not have any water in none of them? What about a warped head?
Additionally could you get the boat up to temp in the drive way hooked up to water to test the comp for the warm compression test? Instead of disabling the pump or backing it back in the lake?
----------------------------------
Last night....I was drunk for a week.
-
I was thinking head gasket but wouldn't it seem weird that all 4 cylinders would be lower in comp and not have any water in none of them? What about a warped head?
Additionally could you get the boat up to temp in the drive way hooked up to water to test the comp for the warm compression test? Instead of disabling the pump or backing it back in the lake?
----------------------------------
Last night....I was drunk for a week.
Kinda sorta.
Let me guess, three point mounts?
If you got it hot enough, you could have blown the web between cylinders.
You have to remember, this is not a car and there is no cooling system pressure without the engine pulling a load.
Good luck.
GT
-
No V8 can lose the fire rings between all 4 cylinders on one side simultaneously. While it's not impossible, I can't see how it's possible.
Do a compression text properly and it will tell the story.
Edit...the only reason I said to run it up to temp was to condition the cylinder walls and burn off fuel/reestablish the oil film so your test results are more useful. Temp makes no difference since it's a comparative test
-
No V8 can lose the fire rings between all 4 cylinders on one side simultaneously. While it's not impossible, I can't see how it's possible.
Do a compression text properly and it will tell the story.
Edit...the only reason I said to run it up to temp was to condition the cylinder walls and burn off fuel/reestablish the oil film so your test results are more useful. Temp makes no difference since it's a comparative test
It only has to do it twice.
And you're wrong. I've seen it. 5-6 and 7-8.
Happened due to what I believe to have been a severe case of hydraulic action from a cracked exhaust manifold.
GT
Sent from my SCH-I545 using SoCal Jet Boats mobile app
-
You must be a ford guy
-
Thanks for the feedback. Sounds to me like I need to re-due the compression test. I did it cold with the throttle in neutral. If I don't add a little oil to the cylinders and have the throttle wide open and fuel wash is a concern would I still get an accurate test? Do I need to run the motor between each cylinder test?
Sent from "The Brown Chair"
-
No, if you don't open the throttle, 2 things will happen. 1, you'll not get adequate intake air to compress to yield a reasonable result and 2, you'll have decent manifold vacuum during cranking which will draw fuel through the carb and effectively flood the engine, which will wash the oil film from the cylinder walls compromising ring seal and making the compression test useless. If you squirt oil in all cylinders, you're artificially improving ring seal...and that oil might even artificially seal up valve/head gasket leaks. If you fire the engine and get it running clean, then shut it down and retest, you'll have an accurate result. You can can the follow that up with a leak down and check any low cylinders for leakage through the breather, intake, or exhaust and determine exactly where your problem lies.
I suspect you'll find nothing wrong and will end up with a simple cooling system issue
-
You must be a ford guy
Nope,
Been called much worse by better people. Hahaha
Just smart enough to know we were talking blue oval.
8)
-
Then learn your damn cylinder positions
Edit. Lol...did' even realize we were talking about ferd. I just looked at it as basic diagnosis.
-
Then learn your damn cylinder positions
Edit. Lol...did' even realize we were talking about ferd. I just looked at it as basic diagnosis.
Immma put this in the win column.
It's pretty much how I roll.
Besides, sometimes when you speak Chevy to a Ford guy they get confused, you know, like when you say start it up and run it.
That's completely foreign to most Ford dudes.
DOH!
GT
-
Sorry Bullzybull... GTjets and I do this from time to time.
-
Ha! No problem at all. I appreciate all you guys and your willingness to get in the trenches to help a guy out! 👊🏼 I got called into work but when I get home I'm gonna try the test over again. I really hope it's just a cooling problem.
Sent from "The Brown Chair"
-
Take a look at both cylinder heads casting numbers and see if they match...it is a nearly 40 year old boat/motor
Big chamber/small chamber mismatch?
Dan'l
-
Take a look at both cylinder heads casting numbers and see if they match...it is a nearly 40 year old boat/motor
Big chamber/small chamber mismatch?
Dan'l
Good call.
-
If you can get your hands on a cylinder leak down tester I'd try that. Just my opinion. If you're local to long Beach I may be able to borrow one and help out
-
Immma put this in the win column.
It's pretty much how I roll.
Besides, sometimes when you speak Chevy to a Ford guy they get confused, you know, like when you say start it up and run it.
That's completely foreign to most Ford dudes.
DOH!
GT
Right when I was kinda startin to like you and your old man wisdom....😏
-
Right when I was kinda startin to like you and your old man wisdom....😏
Well that's because they never shut off...
We good? :D
Hahaha.
GT
Sent from my SCH-I545 using SoCal Jet Boats mobile app
-
Did the leak down test get done yet? If so what were the results?
Shawn
-
Hi guys, I haven't had any time to diagnose the boat yet with work and a full kitchen remodel at the house it's been rough finding the time. But I have made notes with all the info and suggestions you guys have made. I really really appreciate it. I'm hoping to get some new results from the compression test. I will do a cylinder leak down test if needed depending on the results of the compression test. I'll also double check the casting numbers on the heads that's honestly something I would have never thought of. I'll try to have some solid results by sun or mon.
Sent from "The Brown Chair"
-
Ok I got some results from the compression test. Turns out Like probably everyone on here suspected. I did the test wrong! Shocker. All of the cylinders gave good pressure but #8. It came back at 80psi. Besides that. Boat sounds right. Fires up and runs great. Ran the boat for a good 15-20 mins on the hose and temp stayed low around 120. Oil looked good. Hoping to get a leak down tester tomorrow from Harbor freight. I know that should give me a better idea of what's going on. With the info that I have now though, do you think it would be OK to run with that one cylinder at 80?
Thanks again for all your help and feedback!
Sent from "The Brown Chair"
-
With the info that I have now though, do you think it would be OK to run with that one cylinder at 80?
Thanks again for all your help and feedback!
Sent from "The Brown Chair"
Just going to say it.
No.
It really is going to depend what the leak down test comes down to, but two things going through my mind.
One, if it's a rusty cylinder wall, eventually it will have zero compression. It could also be a stuck ring, ultimately cutting away at the cylinder. May be an easy fix now but an expensive fix after it goes all the way.
Two, if it's a valve issue, as hard as these engines run, it could ultimately overheat the valve and drop it into the cylinder, with a great chance of destroying the entire engine.
I honestly think you should investigate further. That's why a compression test is done, to try and prevent small problems from becoming catastrophic.
Good luck.
GT
-
Seriously, dont mess around. I know first hand what a dropped valve does. Pure carnage. Turned that engine into no better than an anchor.
-
Alright, I just did a leak down and I had exactly 20% loss which is in the green on the gauge. Good. So I decided to redue the compression test and I had 120psi. I don't know. Everything seems to be fine now.
All I know is this was a great lesson for newbie on the importance of PROPER diagnostic checks and big shout out to all you guys for all your help especially Ghett0man.
Thanks guys.
Sent from "The Brown Chair"
-
Also I plan on taking a trip to Elsinore tomorrow to see how the boat does under way. I'll post any info that comes from that.
Sent from "The Brown Chair"
-
Also I plan on taking a trip to Elsinore tomorrow to see how the boat does under way. I'll post any info that comes from that.
Sent from "The Brown Chair"
Didn't have time to read all the way back but did you check your pump? Could have sucked something up clogging the cooling line and could have fouled up your pump/impeller . Just a thought
Sent from my iPad using SoCalJetBoats
-
Yea I think that's definately what caused the over heat. Just wanted to make sure no major damage had occurred. So when I got bad results on diagnostic tests it made me worried. But turns out I was doing the compression and leak down wrong. Motor is good to go. Got lucky.
Sent from "The Brown Chair"