I think its time to change my exhaust manifold and elbows

[agaldamez]

i have a 4.3 mercruiser, this year i had a tune up done on the engine the mechanic told me all the spark plugs had rust on them.so he did a tune up and it was starting wonderful. i wonder at that point should he have said something about checking the manifolds?

Now as the summer has gone by it is starting to not turn over every time I try to start it. I will turn the key back and forth then it will finally crank, sometimes its a slow crank.
I purchased the boat used and I have had it for over a year.
I did change out the thermostat because my temperature would never go above 120 degrees. now that i have done that, when i go at high rpm's I am getting to 180 degrees.

I am going to remove spark plugs to see if they have moisture or rust again. If I do, I plan on changing the manifold and the elbows.

Any advice, should i pay someone to do it, should I stick with mercruiser parts. how do i know how much damage has been done to the motor if the manifolds and elbows are leaking.

The engine otherwise seems to be running great.

Any and all suggestions would be appreciative.
thanks

 

[MarkSee]

Re: I think its time to change my exhaust manifold and elbows

Do a little searching here, or someone that knows right off the top of their head might come along, but there's a way to pressure test your cooling system that might help you narrow down if you have water leaking into the cylinders before replacing the exhaust system just to find it might be something else.

Mark

 

[tpenfield]

Re: I think its time to change my exhaust manifold and elbows

As far as replacement of the manifolds & elbows

Mercruiser, Osco, Barr are the decent brand names. I would avoid GLM

You can do it yourself if you are an average wrench turner.

Probably a good time to run a compression test as well as a cylinder leak test to see if the moisture has caused any damage to valves, etc.

 

[achris]

Re: I think its time to change my exhaust manifold and elbows

Need to know a few things. Is the engine the same year as the boat? Are the manifolds 'dry-joint'?

 

[agaldamez]

Re: I think its time to change my exhaust manifold and elbows

im pretty sure the engine is the same as the boat, how can i verify that?

I also am not sure what you mean by Dry joint?

 

[MarkSee]

Re: I think its time to change my exhaust manifold and elbows

im pretty sure the engine is the same as the boat, how can i verify that?

Serial numbers from the engine and drive are the best way to determine exactly what you've got.

If you aren't sure where to find those, check the stickies at the top of the forum as Don has info and pictures that will help.

Mark

 

[agaldamez]

Re: I think its time to change my exhaust manifold and elbows

i checked the serial number and it is a 2002 engine.

Few questions help would be appreciated.

1. Still having starting issues. never an issue when i run muffs, only when its been running in the water for a small period. Again when I turn the key it doesn't turn over right away.

2. Temperature runs 170 min. sometimes hits 180-185. thermostat is brand new at 160 degree.

3. oil pressure running between 60 - 80. i do have to much oil in engine.

4. engine continues to try and run after i tune it off. I am using super non ethanol, and I do wait 30 seconds to let engine idle.

5. If i change the exhaust manifolds where is the best place to get best price.

6. is it timing or is it leaking manifolds and elbows.

7. what are dry joint manifolds??

any help would be great.

 

[tpenfield]

Re: I think its time to change my exhaust manifold and elbows

i checked the serial number and it is a 2002 engine.

Few questions help would be appreciated.

1. Still having starting issues. never an issue when i run muffs, only when its been running in the water for a small period. Again when I turn the key it doesn't turn over right away.

2. Temperature runs 170 min. sometimes hits 180-185. thermostat is brand new at 160 degree.

3. oil pressure running between 60 - 80. i do have to much oil in engine.

4. engine continues to try and run after i tune it off. I am using super non ethanol, and I do wait 30 seconds to let engine idle.

5. If i change the exhaust manifolds where is the best place to get best price.

6. is it timing or is it leaking manifolds and elbows.

7. what are dry joint manifolds??

any help would be great.

#1 - maybe check/replace exhaust flappers. Check the oil to see if you are getting any water in the oil. Water could be getting up inside the exhaust manifolds when the boat is in the water.
#2 - I would run a compression test and a cylinder leak test of the engine. I am thinking about the head gasket(s). A slight leak of the head gasket from the cylinder to the cooling system can cause the cooling system to become partially filled with exhaust gases at high RPM. (possible, so the cylinder testing can verify)
#3 - oil . . . seems a bit high, but you should check the spec's for the engine.
#4 - not sure.
#5 - check here on iBoats for prices. Shop around on the Internet, I would sty with the brands that I mentioned. I have used several places for engine parts I will PM you some of them. Don't get the cheapest, because they are expensive in the long run.
#6 Check timing and check the manifold/riser joint. Replace the gasket if the manifolds and the joint looks good.
#7 Dry joint are a newer version where the water passage to the riser/elbow is separated from the exhaust passage. Any leaking that may occur does not go into the the exhaust (a brilliant idea that only took about 30 years to come around).

I hope this helps.