"hot" spot on engine ?

iskyfly · Post by **iskyfly** » Thu Apr 16, 2009 7:21 pm

05 ATX stock with 67K miles.

Just replaced the plugs (with stock) for the first time (thanks to all the info here).

Prior to and after replacing the plugs I was fooling around with an IR thermometer measuring temps. I noticed that in between spark plug tubes 3 and 4 the temp was around 20 - 30 degrees F higher than in between tubes 1 & 2 and 2 & 3. Now I have no basis for comparison so I dont know if this is "abnormal". Could there be a coolant cavity or oil cavity beneath that area that would explain the temperature difference?

Thanks

OB · Post by OB » Thu Apr 16, 2009 7:56 pm

Where did you take the temperatures? Valve cover or cyl head? It's normal for temps to fluctuate from the front of the engine to the back, for many reasons. Do you suspect a problem or are you just being curious? I don't think it's anything to worry about, but if you have issues then something very well may be going on.

iskyfly · Post by **iskyfly** » Thu Apr 16, 2009 8:13 pm

Just being curious. I am not experiencing any problems (knock on wood). Just wonder why this spot is significantly hotter than the other spots (in between spark plug tubes) As far as where - just on the exterior which I guess would be the valve cover?

Paul56 · Post by **Paul56** » Thu Apr 16, 2009 8:26 pm

The other issue... was the engine fully warmed up at the time of the temperature readings?

iskyfly · Post by **iskyfly** » Thu Apr 16, 2009 8:43 pm

yes. After an hour of highway driving.

Post by **occasional demons** » Thu Apr 16, 2009 10:04 pm

I wouldn't put too much faith in those IR thermometers. Ambient temp plays a huge factor in their accuracy. The one we have at work will tell you the engine is 400+ºF if it is cold outside. Or when in the shop, and it is 90ºF and I point it into some iced water it shows -20ºF

One of those that has the screen that actually shows an image of the temp differences might be a little better than the "point and it displays the temp where the laser spot is" type.

03blackrt · Post by **03blackrt** » Thu Apr 16, 2009 10:08 pm

It’s an inherent design flaw in the engine. It’s really nothing to be concerned about on most applications of the engine.

The problem is that coolant enters at the bottom-front of the engine and exits the top-front of the engine. The coolant will naturally not want to circulate to the rear of the engine with this setup, so it is inherently hotter in the rear. If you look at an OE head gasket you'll see that the shim in the middle layer has restrictions in the front portion to help push more coolant to the rear of the engine and help minimize this flaw.

Donkeypuncher · Post by **Donkeypuncher** » Fri Apr 17, 2009 6:55 am

Different types of plastic and metal absorb and dissipate heat differently. Coatings on top of the plastic/metal may mask these temps as well.

This is why ABS plastic is used for components now, it dissipates heat much better than metal. That's why iceman and k&n are great intakes, they use plastic which retains heat less and dissipates heat better.

Swordfish2Cowboy · Post by **Swordfish2Cowboy** » Fri Apr 17, 2009 12:48 pm

Donkeypuncher wrote:Different types of plastic and metal absorb and dissipate heat differently. Coatings on top of the plastic/metal may mask these temps as well.

This is why ABS plastic is used for components now, it dissipates heat much better than metal. That's why iceman and k&n are great intakes, they use plastic which retains heat less and dissipates heat better.

Too bad K&N doesn't make a plastic intake for the R/T. Just a warm air intake that replaces the stock airbox.

esteinmaier · Post by **esteinmaier** » Fri Apr 17, 2009 1:56 pm

2nd gen neon WAI = a worm clamp from autozone and an air filter.