Hottest part of engine...merc v6

**Scottko** · 06-28-2017, 11:08 PM

Just wondering what part of a merc v6 is the hottest part of the motor. I realize that the exhaust is the hottest, but wondering if the heads or cylinders get hotter than one or the other?

I know on 4 cycle engines, the cylinder head is the hottest part (because the hot exhaust goes through it) but on a 2stroke, the exhaust goes out the side of the cylinder.

**BarryStrawn** · 06-29-2017, 10:40 AM

Center top of the piston is the hottest.

**Scottko** · 06-29-2017, 01:36 PM

I guess I worded my question wrong. What I ment to ask is, What area of the cooling system would be the hottest? The cylinder water jackets, or the head water jackets/water passages?

Thanks.

**BarryStrawn** · 06-29-2017, 03:49 PM

Cylinder heads are last in cooling circuit so have hottest water.

**Scottko** · 06-29-2017, 09:07 PM

OK, that's kinda what I thought, just wanted to make sure.

Brings up a new question, maybe I should start a new thread? What is an acceptable temp at the cylinder head?......1982 200hp 2.4 carbed.

**whipper** · 06-29-2017, 09:17 PM

Top starboard for me last place to exit.

**Krazymaan** · 06-29-2017, 10:57 PM

I use my Milwaukee laser pointer heat temp gun all the time. Its always the top cylinder on the starboard side for me.
I don't normally run my motor for long periods in my driveway, but after 5 mins or so, they usually are between 108 and 135. It varies on the hose for me. Port side is cooler than starboard side. But when you idle up, they tend to even out within' 5 degrees. for me that is. Thats with no stats, no poppet and with 1/4" T-stat washers. on a 1983 carbureted 2.4 Mod Vp at 195psi's of cylinder pressure.

**Steve Pope** · 06-30-2017, 10:02 PM

At full power #5 and#6 combustion chamber. Thats why the F1 engines and I think modified s3000 have the extra cooling hoses discharging extra water into the cylinder heads just above those cylinders combustion chambers.

**Capt.Insane-o** · 07-01-2017, 01:26 AM

Originally Posted by Steve Pope

At full power #5 and#6 combustion chamber. Thats why the F1 engines and I think modified s3000 have the extra cooling hoses discharging extra water into the cylinder heads just above those cylinders combustion chambers.

^^^^

**Poze** · 01-17-2018, 09:15 PM

Bottom cylinders would normally be the hottest and fail the most because they are the most efficient. They do more work because the exhaust has a more efficient path. Just a thought.

**Cervelo777** · 01-17-2018, 11:09 PM

Does anyone have a picture of the extra cooling hose discharge that Steve Pope speaks of? Just curious i melted down #6 and it seems it is the most likely to melt. Just curious.

**BUZZIN' DOZEN** · 01-18-2018, 07:07 PM

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**BUZZIN' DOZEN** · 01-18-2018, 07:15 PM

Originally Posted by Cervelo777

Does anyone have a picture of the extra cooling hose discharge that Steve Pope speaks of? Just curious i melted down #6 and it seems it is the most likely to melt. Just curious.

I'm quite sure the lack of the extra cooling hoses isn't your problem.

**Chaz** · 01-19-2018, 12:22 AM

Originally Posted by BUZZIN' DOZEN

I'm quite sure the lack of the extra cooling hoses isn't your problem.

I had a infrared model of the heat path all mapped out ... but since we have yet to run a little man thru the motor to tell us what he really saw while inside ...

I'm going to concede that your statement is extremely accurate ...

However I'm going to insist that the root of the problem stem's from a common denominator ...