Operating Temperature Question (Updated with pics of impeller body with questions)

[valkyr]

Well finally got my boat back together and I've got some questions about the operating temps. I replaced the temp sensor, hoses, thermostat.

Now, I don't know much about risers, but it appears the risers have separate chambers? Is that correct?

The thermostat is 143 degree thermo. What should the running temps of the risers (each 'chamber') be (approximate) and the temp of the manifolds?

Also, what is an acceptable difference between the risers (port & starboard) and the difference between the manifolds (port & starboard).

I seem to have about a 25 degree difference between port and starboard sides on the manifold and about the same on the risers.

My port manifold seems to be about 150-155 degrees, my starboard manifold seems to be running about 175-180 degees.

My port riser where the water goes in seems to be around 110-125 degrees, the starboard riser where the water goes in seems to be around 80-90 degrees.

The water coming out of the manifolds seems to be about the same temp - 130-140 degrees.

I'm using one of those infrared thermometers.

Thoughts?

 

[bjcsc]

Re: Operating Temperature Question - A lil' help?

Re: Operating Temperature Question - A lil' help?

Are you running these temp tests on the hose or on the water? It is normal for one side to be warmer than the other on the hose, but they should be very close on the water. That said, 180 is too high regardless. It could be your bow shot. Have you separated the riser/manifolds and inspected them? The both have separate chambers: 1 for exhaust (inner) and 1 for water (outer)...

 

[valkyr]

Re: Operating Temperature Question - A lil' help?

Re: Operating Temperature Question - A lil' help?

"Bow shot"?

I'm scanning the hoses, the risers themselves, the manifolds, and inlet ports, and the outlet ports.

 

[valkyr]

Re: Operating Temperature Question - A lil' help?

Re: Operating Temperature Question - A lil' help?

I was running on muffs also, would that cause the temp issues?
Also I only noticed them when idling around 1500rpm instead of 1000rpms.

Anyone else have input?

I really don't "want" to take the risers off because then I have to replace the gaskets between the manifolds and risers?

 

[Don S]

Re: Operating Temperature Question - A lil' help?

Re: Operating Temperature Question - A lil' help?

Put the boat in the water and run it and see what happens.

I really don't "want" to take the risers off because then I have to replace the gaskets between the manifolds and risers?

Those gaskets don't last forever. If they are over 3 years old, pull the danged things and LOOK. What is more expensive, your engine or those gaskets.
Your choice.

 

[Bt Doctur]

Re: Operating Temperature Question - A lil' help?

Re: Operating Temperature Question - A lil' help?

Hmmmmmmm,Lets See
A $6.00 gasket or a $6000 Motor.
You know what, You decide

 

[valkyr]

Re: Operating Temperature Question - A lil' help?

Re: Operating Temperature Question - A lil' help?

Ok ok ok....I'll pull the risers. :redface:

What should I be looking for? I've never seen in the inside of a riser or a manifold.

Put the boat in the water and run it and see what happens.

Don, I think you were being sarcastic here...but I wanted to be sure.

Thanks!

 

[Don S]

Re: Operating Temperature Question - A lil' help?

Re: Operating Temperature Question - A lil' help?

No, I wasn't being sarcastic.
Run it and see what is happening for real, not just on a hose. You may have water pressure issues you have no control over or too long a hose and too little water pressure. Who knows. Put the boat in the water and see what the pump does. Hopefully it's new.

 

[valkyr]

Re: Operating Temperature Question - A lil' help?

Re: Operating Temperature Question - A lil' help?

I've decided to pull the risers, but I need to know what to look for. I guess I can take pictures and let you guys tells me what looks bad or good.

I read somewhere a few minutes ago that "if there is corrosion at the joint between the riser and the manifold" then the gasket has failed. My port riser/manifold joint is corroded so I need to go ahead and pull them anyway.

I haven't replaced the impeller on this boat either. I've only owned it a year. So if I need to replace the impeller, what do I need? Just the impeller or more than that? I think I read somewhere when replacing the impeller on these engines that you were supposed to replace something else...the housing or something?

Thoughts?

 

[Don S]

Re: Operating Temperature Question - A lil' help?

Re: Operating Temperature Question - A lil' help?

I haven't replaced the impeller on this boat either. I've only owned it a year.

This has been said in every overheat post that I have ever posted (I think, maybe missed a couple)


The raw water pump impeller is the FIRST thing you check in any overheat problem. There are just to many things that can destroy the impeller.
Since you seem to be new here, get an OEM service manual for your engine, it tells you how to dissassemble, inspect, repaire or replace the raw water pump.

 

[valkyr]

Re: Operating Temperature Question - A lil' help?

Re: Operating Temperature Question - A lil' help?

I'm not new here (Well been here over a year anyway)

I have the service manual, but it seems like I saw somewhere that on these 454 7.4L engines, there is something besides the impeller that needs to be replaced related to the raw water pump.

The location of the raw water pump makes it difficult to just pull and inspect.

 

[Don S]

Re: Operating Temperature Question - A lil' help?

Re: Operating Temperature Question - A lil' help?

The location of the raw water pump makes it difficult to just pull and inspect

No S*** **** Tracy, what do you think marine techs do on a daily basis when the customers think we should know all this stuff without ever looking.
We aren't miracle workers, we get into those dumb positions (no matter what it takes) and take things apart and inspect. We remove risers, even when they are under panels and not even visable. Working by brail is SOP (Standard Operating Procedure) for a Marine tech.
If it was easy, everyone would do it.

 

[bjcsc]

Re: Operating Temperature Question - A lil' help?

Re: Operating Temperature Question - A lil' help?

"Bow shot"?

I'm scanning the hoses, the risers themselves, the manifolds, and inlet ports, and the outlet ports.

By "bow shot" I meant warning, as in naval warfare. If all else is normal, when you see temps creep up, esp. on one side, that's your warning to check the manifolds/risers, etc.. We all know where the next shot lands...

I'd run it in the water before I did anything else. See if you get the same temp results...IR thermometers are great for this...report back what you find. If you end up pulling your risers, take pics of the mating surfaces and post them if you can't tell anything. I think you'll probably find scale/blocked passages in the hotter side. Don't forget risers and manifolds are "consumables"...

 

[dasnively]

Re: Operating Temperature Question - A lil' help?

Re: Operating Temperature Question - A lil' help?

If the impeller comes apart, it can block the water supply the the risers. I agree with Don, start with the impeller, it's the first and easiest thing to fail. And be very careful about running the engine above idle on muffs, you'll suck the hose flat without realizing it.

 

[valkyr]

Re: Operating Temperature Question - A lil' help?

Re: Operating Temperature Question - A lil' help?

No S*** **** Tracy, what do you think marine techs do on a daily basis when the customers think we should know all this stuff without ever looking.
We aren't miracle workers, we get into those dumb positions (no matter what it takes) and take things apart and inspect. We remove risers, even when they are under panels and not even visable. Working by brail is SOP (Standard Operating Procedure) for a Marine tech.
If it was easy, everyone would do it.

Ok, Don I understand I'm an idiot. :redface:

Now, would you mind helping me to know if I can just replace the impeller only on this raw water pump, or is there something else I need. Because I swear I read somewhere that when replacing the impeller on these units there was something else that needed to be replaced. Like the housing or cover or something?

 

[valkyr]

Re: Operating Temperature Question - A lil' help?

Re: Operating Temperature Question - A lil' help?

Bjcsc: Thanks for the clarification of bow shot. I know I've got to take apart the risers because one of them has rust between the riser and the manifold which apparently is a "sure sign the water jacket has failed". *sigh*

So, I'll be taking apart the risers and more than likely replacing them.

Do you normally replace the manifolds at the same time, or does it just depend?

Das - thanks for your input as well.

 

[Don S]

Re: Operating Temperature Question - A lil' help?

Re: Operating Temperature Question - A lil' help?

Check the surface areas of the manifolds and risers where the gaskets seal.

Ok, Don I understand I'm an idiot.

Don't get all excited about my comments. Your comment about it being difficult to pull and inspect, caught me after working on a job very similar. No access, can't see it, can touch it with one hand, takes three hands to do the job, and the customer is whinning about how long it takes to work on his boat. That is also why I never INSPECT a pump like that. If I go to all the work to take it apart, it gets a new impeller. No questions ask.

 

[valkyr]

Re: Operating Temperature Question - A lil' help?

Re: Operating Temperature Question - A lil' help?

Don,

I wasn't worried about your comments. I've been around long enough to know you know what you're talking about and I'm also old enough to know when I'm being an idiot LOL

However, I still need to know if I just need the impeller (when I get the pump off) or more? I think I need the back cover and some other "stuff"?

I checked the impeller kits, but I wasn't sure EXACTLY which kit I needed. Could you advise which kit I need?

Thanks again for all your help!

 

[Don S]

Re: Operating Temperature Question - A lil' help?

Re: Operating Temperature Question - A lil' help?

However, I still need to know if I just need the impeller (when I get the pump off) or more? I think I need the back cover and some other "stuff"?

Look at it. If it's nice and smooth, no deep grooves, or melted areas, or ???? then it's probably fine. Hate to tell you this, but it's hard to give advise on needing a possibly worn part when I can't see it.
Do you have a pump with the one piece body or the two piece body/end cap?

 

[valkyr]

Re: Operating Temperature Question - A lil' help?

Re: Operating Temperature Question - A lil' help?

Look at it. If it's nice and smooth, no deep grooves, or melted areas, or ???? then it's probably fine. Hate to tell you this, but it's hard to give advise on needing a possibly worn part when I can't see it.
Do you have a pump with the one piece body or the two piece body/end cap?

Ooohhhh my bad.

I didn't realize there were two different types for my engine serial number.

Here's the part number and a close picture of what I have:

46-807151A 12