VP 5.0L SX port riser hot to touch

[harojs]

1995 VP 5.0L SX 550hrs on 1969 24ft Tolly

Just had both risers, manifolds, and flappers replaced with new OEM parts and I seem to be running at 170F at guage.The stbd riser is 84.5F and the port is 102.5F. Will shoot the thermostat temp when I check next.

Going to check all seawater input hoses, and then check port flapper for proper operation.

HE flashlight test shows 90% clear tubes.

I did have a seawater impeller failure prior, and decided to change out risers and manifold while we were at it. There may be impeller bits blocking something.

[Q] Which supply is the steering pump cooler on this engine? Could that be restricting?

Other items I should check or test?

 

[Scott Danforth]

if you have an impeller failure, you must tear the system apart looking for the pieces.

power steering cooler is on the inlet side of your raw water pump.

clean your HX.

 

[Silverbullet555]

Check the oil cooler while you are at it. Backflush all the coolers and look for pieces.

I battled a difference in riser temps for quite a while. Are you sure it didn't exist prior? Are your riser temps at idle? Are they in the water or on the hose? How do they change at speed?

I eventually put clear hose into my system so I could see flows. I determined one side was not flowing well enough but could never determine why. I finally restricted the good flowing side forcing more water into the other side which actually flows fine. It was some sort of hydro dynamic issue and path of least resistance. It balanced my temps out.

Was it worth it? Couldn't tell you. In the course of it I spent countless hours, replaced the raw water pump and thermo housing, and spent a total of about a thousand dollars. The temps are balanced, but I can't say it was really more than a ghost and something I didn't like vs something I really needed to do.

 

[Lou C]

If that is a Volvo I/O style engine the P/S cooler could be on the back of the engine behind the starboard side exhaust manifold/elbow. Your 20* difference in temps is not really concerning. I have a Volvo style center riser exhaust on m '88 OMC 4.3 and on the water hose the tops of the elbows (risers) don't even get warm. They are like 75-80*.
What I would be more concerned with is how hot they get when running on plane. When I had the OMC batwings on mine they would get up to about 135* max and then cool down to about 100 after idling about 10 min. When all was right with the cooling system it would run at 160 and the max would be 175 after coming off plane. While you are at it make sure all the ports in the thermostat housing are open, they neck down from corrosion in raw water cooled engines.

 

[harojs]

Thanks all,

I am seeing 170 all the time, in water, and on hose. Prior to new seawater pump and risers/manofolds, I thought I was getting 160, (on helm guage 160 pref temp mark), all the time on plane and hose, and I could touch both risers.

[Q] Are there two thermostat types/values for the 5.0L? If so, which one is best for closed system in salt water?

I think I will start by checking thermostat to see if its stuck, even replace it since I'm in there. Then maybe replace hoses to risers with clear to see if that sheds any light on diff riser temps.

[Q] Is running at 170 bad for the VP 5.0L?

 

[Misterbulbous]

Thanks all,

I am seeing 170 all the time, in water, and on hose. Prior to new seawater pump and risers/manofolds, I thought I was getting 160, (on helm guage 160 pref temp mark), all the time on plane and hose, and I could touch both risers.

[Q] Are there two thermostat types/values for the 5.0L? If so, which one is best for closed system in salt water?

I think I will start by checking thermostat to see if its stuck, even replace it since I'm in there. Then maybe replace hoses to risers with clear to see if that sheds any light on diff riser temps.

[Q] Is running at 170 bad for the VP 5.0L?

I'm pretty sure the thermostat for the closed system is a 140F type. If you've removed the old thermostat, you should see the tempertaure rating imprinted on the flange. By the way, I recently had a concern that my 160F thermostat was faulty...I did a controlled experiment and found that it was actually opening up around 172~3, so I thought maybe it was bad. Bought a new one rated for 160 and it also opens up around 172.

 

[harojs]

[Q] What should normal operating temp typically be on 5.0L at top of Tstat housing if I shoot it with IR gun?

 

[Misterbulbous]

[Q] What should normal operating temp typically be on 5.0L at top of Tstat housing if I shoot it with IR gun?

I shot mine with a FLIR infrared camera last night. I don't have the pictures/data with me, but I'll try and post tonight. If I recall, it was running between 170~175. I'll confirm for you.

 

[Lou C]

Take readings of the elbows in the water at idle, and after running on plane. For the engine temps, I found the best spot to check is the intake manifold right under the thermostat housing.

 

[harojs]

[Q] What is the technical explanation that one manifold/riser will always run hotter than the other in a normal condition?

My port riser is running 84.5F and my stbd riser is running 102.5F measured at top of riser with IR gun in water and on hose. That normal for brand new manis and risers raw water mani cooling?

 

[alldodge]

My port riser is running 84.5F and my stbd riser is running 102.5F measured at top of riser with IR gun in water and on hose. That normal for brand new manis and risers raw water mani cooling?

Your temps look normal

 

[harojs]

I found problem. I had an old flapper stuck down in the Y-pipe on the stbd side, which was the hot side. I looked at the seawater cooling input to the manifold, and that was clear. I bought a $36 wireless Endoscope that displays to my Android, and after opening up the elbow I could see the old flapper down in the Y-pipe. I have to get some heavier clothes hanger wire and try to dig the old flapper out of there. Will keep you posted. That Endoscope is great.

 

[harojs]

• I GOT THE BUGGER! Endoscope worked great. I was able to insert the scope in at my riser hose junction initially to verify if old flapper was down in ypipe without taking the elbow apart. I could see the new flapper and then went down from there to see the old flapper. I then took the whole elbow and new flapper out. Using the scope to guide me and a bendable steel rod, blue tip at home depot, I fished it out. Took about an hour of fishing before i got it out as flapper was jammed in a bit.
  
  Endoscope to phone was only $36 and worth every penny.
  
  My port riser is cool to the touch now, however my stbd seems to be hot now as i think port side is so clear system is not balanced, something maybe plugging stbd also.
  
  I will check to stbd now to see if maybe old flapper might be down on that side too.
  
  What pisses me off is the shop must not have even looked down the pipe to see if old flappers were down there when they installed my new risers and manis.

 

[Lou C]

Great save! You might have had to remove the drive depending on how far down it was.

 

[harojs]

I saw on another post that muffs don't count when testing cooling problems, house pressure vs raw water pump pressure. Does it matter which side of SX intake holes single port muffs are put on? Trying to figure out why my stbd riser is suddenly hotter than my port riser after port riser cleared of stuck flapper. (running with muffs on port SX intake). Air gap in stbd riser? Maybe I need to test now with boat fully in water?

 

[alldodge]

One will always be hotter then the other, on hose or in the water. They should never be hot enough to burn if touched

 

[harojs]

Well, I endoscoped the stbd exhaust. New flapper was in place correctly. No old flapper down in that side of Y-pipe, and input cooling hose to stbd mani is clear.

I am going to test in the water later this week, I am thinking running on the hose does not supply a full enough volume of raw water that is needed to balance flow to both manis and risers and one side ends up hogging all the flow making the other side hotter.

[Q] Are flappers supposed to move super-loosely? The new flapper in my stbd side is in correctly, it moves correctly, but does not flap super-freely. I am thinking once the rpms and exhaust pressures are up they would open accordingly though. I put a little oil on the flapper rubber bushings anyway. I know,... it'll probably wear off after a bit.

 

[alldodge]

They don't move easy

 

[harojs]

Cool, I thought flappers might operate fine with non-loose movement. I do not like the rubber bushings on the flapper shaft, seems like they would fail easy or early. Guess I should look at, or replace, flappers once a year. Certainly after any overtemp event.

 

[alldodge]

Flappers normally last a long time except after an over heat. VP stopped installing flappers some years ago, Merc still does