enginesilo
Petty Officer 1st Class
- Joined
- Jun 9, 2008
- Messages
- 355
What is too hot for an exhaust manifold on a 3.0L engine? I'm testing on the hose, not in the water. What is a common temperature for the manifold on a 3.0L to get up to?
The thermostat seems to kick in around 175 and brings the temp down to 160 as it normally does, and it cycles between that. I checked around the engine with an IR thermometer and most of the block is around 150-160 with the hottest spot being near the spark plugs around 170 at its hottest. However, right where the manifold meets the block (On the block side), I was getting temperatures closer to 200-225 degrees. Seems like it is hottest closest to the thermostat side, and it gets cooler as it goes back with the temp towards the back in the 150 range. Is it normal for this to be the hottest spot and is this normal, or is this too hot? The manifold itself is under 170 anywhere I check and even cooler in some spots depending on where I check it. It is just that area right on the block side where the block meets the manifold, maybe 1/2" into the block side. The riser was changed last year and runs cool as a clam, always under 100 degrees, and the water exiting is able to be touched and is not that hot.
So most of the engine is within the 150-170 range, its only this one area on the upper block where it meets the exhaust manifold. Is this spot on the block where it meets the manifold way too high temperature wise, or is the exhaust temperature right at this spot expected to be higher since its right where its entering the manifold? Or is this a sign my manifold is in bad shape? The manifold is definitely old, but I was considering changing at a later time since I don't have the time to do it now.
I do slip the boat all season in salt water. I changed the riser last year, and I pulled it last week to inspect and I was surprised that the manifold still looked decent, at least where it meets the riser. They are original and about 10 years old. On the outside, it looks brand new, no rust. I know these rot from the inside out though. Attached is a picture of what the manifold looks like.
The thermostat seems to show temperature as normal in the 160-175 range as it cycles.
Another forum member mentioned it may be ok since the water jackets don't run in this area, but I'm not sure if 200+ is TOO hot for any area of the motor.
I may try to bring it to the launch and put it in the water and see if I get the same temps. Its just that one area that seems hotter than the rest so it has me concerned.
Is it normal for temperatures to be higher in this area, or am I in trouble?
I want to get using the boat this weekend, or I'll just need to hold off and change the manifold.
All opinions appreciated!
Thanks!
The thermostat seems to kick in around 175 and brings the temp down to 160 as it normally does, and it cycles between that. I checked around the engine with an IR thermometer and most of the block is around 150-160 with the hottest spot being near the spark plugs around 170 at its hottest. However, right where the manifold meets the block (On the block side), I was getting temperatures closer to 200-225 degrees. Seems like it is hottest closest to the thermostat side, and it gets cooler as it goes back with the temp towards the back in the 150 range. Is it normal for this to be the hottest spot and is this normal, or is this too hot? The manifold itself is under 170 anywhere I check and even cooler in some spots depending on where I check it. It is just that area right on the block side where the block meets the manifold, maybe 1/2" into the block side. The riser was changed last year and runs cool as a clam, always under 100 degrees, and the water exiting is able to be touched and is not that hot.
So most of the engine is within the 150-170 range, its only this one area on the upper block where it meets the exhaust manifold. Is this spot on the block where it meets the manifold way too high temperature wise, or is the exhaust temperature right at this spot expected to be higher since its right where its entering the manifold? Or is this a sign my manifold is in bad shape? The manifold is definitely old, but I was considering changing at a later time since I don't have the time to do it now.
I do slip the boat all season in salt water. I changed the riser last year, and I pulled it last week to inspect and I was surprised that the manifold still looked decent, at least where it meets the riser. They are original and about 10 years old. On the outside, it looks brand new, no rust. I know these rot from the inside out though. Attached is a picture of what the manifold looks like.
The thermostat seems to show temperature as normal in the 160-175 range as it cycles.
Another forum member mentioned it may be ok since the water jackets don't run in this area, but I'm not sure if 200+ is TOO hot for any area of the motor.
I may try to bring it to the launch and put it in the water and see if I get the same temps. Its just that one area that seems hotter than the rest so it has me concerned.
Is it normal for temperatures to be higher in this area, or am I in trouble?
I want to get using the boat this weekend, or I'll just need to hold off and change the manifold.
All opinions appreciated!
Thanks!
Last edited:
Temperature of combustion is around 1,000
