Hood vent design debate

[Greenz]

Replaced the fuel injectors w/4 hole and DEI insulation kit today. Thought you all might like some pictures.

First is the Chrysler installed heat shield installed in 01 or 02. I took it out very carefully to show how much it fell apart over the years. In contrast the new one is about a quarter inch thick. It was heavy like it was soaked in oil and dirt compared to the new one.

Replaced the Injectors and found this mess. Had bad heat soak and mis-fires on Cyl 2 & 3 setting codes if I didn't allow a full cool down between running. Hmmmmm?????

Did the rain water damage them? I think I'm eating crow.

Took it for a city drive stopped for ten minutes to check for heat soak condition. ... and it's gone!

 

[bigdaddyjlove]

That damage isn't from water. I've had that happen on two late models that were kept stock. One with the pre-cats, one without. I think its just heat, but I can't prove it.

 

[Greenz]

That damage isn't from water. I've had that happen on two late models that were kept stock. One with the pre-cats, one without. I think its just heat, but I can't prove it.

Good to know. Did you have heat soak or mis-fires?

 

[Rockwood]

Replaced the fuel injectors w/4 hole and DEI insulation kit today. Thought you all might like some pictures.

First is the Chrysler installed heat shield installed in 01 or 02. I took it out very carefully to show how much it fell apart over the years. In contrast the new one is about a quarter inch thick. It was heavy like it was soaked in oil and dirt compared to the new one.

Replaced the Injectors and found this mess. Had bad heat soak and mis-fires on Cyl 2 & 3 setting codes if I didn't allow a full cool down between running. Hmmmmm?????

Did the rain water damage them? I think I'm eating crow.

Took it for a city drive stopped for ten minutes to check for heat soak condition. ... and it's gone!

Classic embrittlement.

https://en.wikipedia.org/wiki/Embrittlement

https://en.wikipedia.org/wiki/Thermal_degradation_of_polymers

The chalky surface is usually the first sign. Look at most of the plastic under the hood of your Jeep and you'll probably see similar signs. Good thing you caught it when you did, that was a fire waiting to happen.

You could leave plastic underwater indefinitely without harm other than just time.

Did you have hood vents?

 

[bigdaddyjlove]

Good to know. Did you have heat soak or mis-fires?

The one with pre-cats had heat soak issues.

 

[trippled]

The way I see it, they're not some be all end all thing. But if they offer some relief for whatever then I'll take that. If the stock cooling system is fine then you don't need that high dollar aluminum radiator and high flow water pump right?

I have a small set of vents on mine. Been on there for like 10 years. Ive lost 1 tps in that time a couple years ago. And yea the vents get insanely hot. After a quick drive the whole hood can be covered in snow except for the vents.

 

[Greenz]

Classic embrittlement.

https://en.wikipedia.org/wiki/Embrittlement

https://en.wikipedia.org/wiki/Thermal_degradation_of_polymers

The chalky surface is usually the first sign. Look at most of the plastic under the hood of your Jeep and you'll probably see similar signs. Good thing you caught it when you did, that was a fire waiting to happen.

You could leave plastic underwater indefinitely without harm other than just time.

Did you have hood vents?

Good info...

Yes I have hood vents over top of the injectors. I guessed the water ran down the injectors where the black and blue plastic meet. Once the rust started it expanded radially cracking the plastic. But if this can happen without vents, I can't explain it other than embrittlement from heat.

 

[Black1990jeep]

How about simply popping the hood when stopped when it is hot? add a spacer as needed, tennis ball maybe. just besure to secure before driving away! Maybe extend the safety catch length to allow it to still be effective with hood raised in front an inch or two, just incase you forget to close it all the way.

For slow offroading, pop the hood when driving, maybe add some hood pins to secure front of hood in slightlyraised position so it dont bounce when offroading. then remember to put hood closed for highway use? I assume a slighty open hood would reduce airflow thru radiator when on the highway, but would not be a problem for slow offroad driving.

Viable option or stupid idea?

 

[Rockwood]

How about simply popping the hood when stopped when it is hot? add a spacer as needed, tennis ball maybe. just besure to secure before driving away! Maybe extend the safety catch length to allow it to still be effective with hood raised in front an inch or two, just incase you forget to close it all the way.

For slow offroading, pop the hood when driving, maybe add some hood pins to secure front of hood in slightlyraised position so it dont bounce when offroading. then remember to put hood closed for highway use? I assume a slighty open hood would reduce airflow thru radiator when on the highway, but would not be a problem for slow offroad driving.

Viable option or stupid idea?

I tried it, didn't seem to work well. I think the fans are helped a little by the proximity of the hood. The air leaving the fans would have to make a 180* turn to leave as well, and any heatsoak from the motor would have to cross the air curtain from the fans to leave.

 

[Bent]

For slow offroading, pop the hood when driving, maybe add some hood pins to secure front of hood in slightlyraised position so it dont bounce when offroading.
Viable option or stupid idea?

The Latched hood acts as a sheer panel. Personally I would leave it latched off road.

 

[randy57]

Hood vents are for dissipating heat to help with preventing heat soak, Not for engine cooling.
If people want to laugh that's on them, I'm sure the laughers do stupid things too that make others laugh at them behind their back.
Besides we don't get enough rain in AZ southern to matter.

 

[Rockwood]

Hood vents are for dissipating heat to help with preventing heat soak, Not for engine cooling.
If people want to laugh that's on them, I'm sure the laughers do stupid things too that make others laugh at them behind their back.
Besides we don't get enough rain in AZ southern to matter.

But the same engineers who threw the D35 in the XJ designed the cooling system!

 

[Bent]

But the same engineers who threw the D35 in the XJ designed the cooling system!

And the hinge setup on the two door.

 

[sinat01]

And the hinge setup on the two door.

and an aluminum steering box spacer arty:

 

[Bruce L]

I was lucky enough to find a rare set with gutters ,that came from a Grand Cherokee which had a 5.9 from the factory .no water what so ever and temp guage has went down a full 10 degrees .Here in the St Lou area we get hot and humid .My XJ is a 94 .4.0 .

 

[Cottontail]

I put LeBaron vents on mine years ago. Never had any overheating issues, and still don't. When I sit at a red light and can see physically see the heat rising out through the vents, I know that it is doing something to dissipate the under hood heat.

I'm sure that the Jeep would have been fine without them. However, I like the way they look, they were an easy mod, they haven't had any negative affects to the way the Jeep performs, water intrusion hasn't been a concern. I'm happy with my decision.

 

[Rockwood]

I was lucky enough to find a rare set with gutters ,that came from a Grand Cherokee which had a 5.9 from the factory .no water what so ever and temp guage has went down a full 10 degrees .Here in the St Lou area we get hot and humid .My XJ is a 94 .4.0 .

Nice!

Still scouring junkyards for an acceptable solution before my Rubicon trip. While I don't anticipate cooling issues, I also don't like the idea of holding up a crew that isn't powered by heaters with crank output like my XJ (22RE 4Runner, 3 JKs) because of a failure.

 

[Ralph77]

I was lucky enough to find a rare set with gutters ,that came from a Grand Cherokee which had a 5.9 from the factory .no water what so ever and temp guage has went down a full 10 degrees .Here in the St Lou area we get hot and humid .My XJ is a 94 .4.0 .

Nice!

Still scouring junkyards for an acceptable solution before my Rubicon trip. While I don't anticipate cooling issues, I also don't like the idea of holding up a crew that isn't powered by heaters with crank output like my XJ (22RE 4Runner, 3 JKs) because of a failure.

Me too. Can't post a picture here but you can see my '00 here at Post # 84139:

http://www.jeepforum.com/forum/f177...j-mj-today-566549/index5610.html#post36316153

 

[maxbraketorque]

...

That being said: I did notice a significant decrease in coolant temps using the factory recommended 10w30 over 10w40. If you're running heavier oil, try going to factory fill (assuming sufficient oil pressure) and see if it helps. Between that and a ZJ fan clutch, I haven't had any issues with temperatures and the auxiliary fan rarely turns on.

Older thread but interesting comment about 10w30 vs 10w40. I'm wondering if anyone else has experienced a difference in operating temperature between the two oils.

 

[RCP Phx]

Older thread but interesting comment about 10w30 vs 10w40. I'm wondering if anyone else has experienced a difference in operating temperature between the two oils.

It's possible but it be due to other reasons. A lot of new motors are designed to run on 5-20w but that doesn't mean they produce less heat. Something else would have caused the change just like excessive oil pressure actually increases friction(heat).