Hi All,

I got the itch to fix something on the pathy (and hopefully avoid a future breakdown), the wife is currently on maternity leave so we can get by with one car so now is probably a good time to make some mistakes. Here are the ideas I have...

Coolant system:
- hoses are probably fine. But I suspect that the plastic connector to the heater core is probably pretty brittle. Should I go grab hoses and wiggle the radiator connections to see if they are about to break. Also, something similar by the rear heater core. If I have to break into the system I will probably do the thermostat as well.

Engine:
- engine isn't running super smooth at idle - seems to shake a little. No codes (all but one injector is original and spark plugs are fairly new). I am suspicious of the engine and transmission mounts. I do have a lift, but the transition seems to hang below the crossmember. I wonder if this is normal or if the trans-mount is shot. Also, I have suspected the engine mounts to be shot for some time but I just haven't found any way to verify this and the mounts aren't cheap.

So, am I just a dummy looking for a problem or a smart guy avoiding a roadside breakdown?

BTW. its a 2007 4x4 S with a 2-2.5 lift and about 126k.

On an '07, you know that plastic coolant manifold is gonna break. The stuff embrittles 100% of the time with old age. So that isn't a question of if, but when. I'd call that a stitch in time, not chasing trouble.

Mounts are easy to check, but you need an assistant. Have someone work the shifter D -> R -> D -> R repeatedly and give it a little gas between shifts. Healthy mounts should only let the engine lift a little, maybe an inch or so. If it's visibly banging around when it's gassed in gear, one or both mounts are shot. If they're really far gone you'll probably get a little "bang" when the engine torques. The tranny mount can be checked the same way but you need to crawl underneath, if the tail of the tranny is bouncing up and down like a rubberball with each shift then that mount is shot.

Definitely go with the coolant lines at the firewall. Valve cover gaskets and coil packs if you haven't done them.

silverarrow27 wrote: ↑

Sat Jul 22, 2023 10:48 pm

Definitely go with the coolant lines at the firewall. Valve cover gaskets and coil packs if you haven't done them.

I had one of the coils fail already. I replaced it with an OEM one. Do the coils tend to expire at the same time? It does run a little rough at idle (slight shaking of the vehicle). Would the coils cause this? I saw the Z1 coils thread there. it is nice to see that those are not 100$ a piece + like the oem ones.

valve cover gaskets were replaced not too long ago.

AS_The_Crow_Flys wrote: ↑

Thu Jul 27, 2023 4:16 pm

Do the coils tend to expire at the same time?

Yes if they're all very old, or if the vehicle grounds are getting dicey.

AS_The_Crow_Flys wrote: ↑

Thu Jul 27, 2023 4:16 pm

It does run a little rough at idle (slight shaking of the vehicle). Would the coils cause this?

Yes. Plugs too, or carbon buildup, or a lot of things. But can coils cause it, positively.

After my heater manifold detonated, I would rather have done it pre-emptively.

VStar650CL wrote: ↑

Wed Jul 19, 2023 3:21 pm

On an '07, you know that plastic coolant manifold is gonna break. The stuff embrittles 100% of the time with old age. So that isn't a question of if, but when. I'd call that a stitch in time, not chasing trouble.

Mounts are easy to check, but you need an assistant. Have someone work the shifter D -> R -> D -> R repeatedly and give it a little gas between shifts. Healthy mounts should only let the engine lift a little, maybe an inch or so. If it's visibly banging around when it's gassed in gear, one or both mounts are shot. If they're really far gone you'll probably get a little "bang" when the engine torques. The tranny mount can be checked the same way but you need to crawl underneath, if the tail of the tranny is bouncing up and down like a rubberball with each shift then that mount is shot.

Do you have the exact parts number of those plastic coolant manifold parts for a V8?
What about the coolant hoses that go into the heater core , they should get replaced too yes?

This is one of the hoses that goes to the heater core from the back of the engine that has a bulky device inline on the hose - 92400-ZS21A. Unfortunately the longer one that comes out from the rear driver side is no longer available. I bought a Samco hose to see if that'd work, but it was too big unfortunately. Maybe I'll try a smaller Samco hose next year as they're quite spendy.

This is the plastic assembly for the VK56 - 92408-ZS20A.

Seems like a good time to consider the hoses and any other plastic coolant system parts. Isn't the thermostat housing normally plastic? so maybe replacing that would be a good idea (I may be wrong on this). something like this... note this raises the question, should we use a stock temperature range thermostat or a lower range thermostat?
https://www.z1offroad.com/water-pump-fa ... d+Products


What about coolant hoses... should we be going silicone. (this is a kit with all kinds of hoses)
https://www.z1offroad.com/z1-products/z ... a1e40c1a03

There is also this billet version of the heater hose inlet connector
https://www.z1offroad.com/z1-products/z ... edTogether

instead of this scary looking plastic bit
https://www.z1offroad.com/heater-piping ... 63078bfea4

weird thing is i do not see an upgraded version of the heater hose outlet.

Replying to my own thread, but i found this. Its for dual air... I assume that means separate rear AC control but i would have to look. i have a 2007 S 4wd so not sure this would work with mine.

https://www.wholesalepartsexpress.com/p ... -dual-air/

it was from this video
https://www.youtube.com/watch?v=CPpNtn2bmAQ

I also found these dorman parts that may work to replace the parts on more of a budget without the plastic.

Heater hose assembly for those with Rear HVAC (dorman part number 626-688)
https://www.dormanproducts.com/p-139993 ... 83954cc%29

I think these two are for pathfinders without the rear HVAC.
Dorman Part number 626-610
https://www.dormanproducts.com/p-104268 ... 83954cc%29

Dorman Part number 626-598
https://www.dormanproducts.com/p-129535 ... 83954cc%29

I would definitely go with the upgraded thermostat housing with factory Nissan oem thermostat. You don't need a low temp one since it's no race car nor you probably don't do any spirited driving with it, it'll just end up causing the engine to run rich burning more fuel. I'd go with the billet heater hose inlet so you buy once cry once. Coolant hoses is up to you whether you want to stay with the factory hoses which can get pricey or you can go with a silicone hose kit which will usually contain most of the major ones. I went with a silicone set on mine recently and supplemented with Nissan OEM wherever needed. As for the Dorman coolant lines, I'd go with them. I did hear one or two complaints about rust either from the X or Frontier forum though.

Hi All,

So I decided to take care of the hoses and coolant system (I have at least one coolant hose with a rather concerning crack. So I ordered the master hose kit. Given the price of OEM hoses I figured this was either cheaper or at least easier to do than try to piecemeal things. I ordered black because I though the red/blue would look tacky but that is just me.
https://www.z1offroad.com/z1-products/z ... a1e40c1a03

I also ordered the billet inlet replacement with the bleeder on it. Given the past difficulties getting the heater core bleed i figured it was worth the few extra dollars over the dorman part.
https://www.z1offroad.com/z1-products/z ... edTogether

The only non-plastic version that I could find for the heater core outlet was the dorman part below so I ordered that as well.
https://www.amazon.com/Dorman-626-598-E ... B00KQJ1YOQ

I also ordered an OEM thermostat and gasket because well (z1 sells it)... if I am doing all this I might as well do that also.

Does anyone know what size vacuum hoses are needed and the lengths? I know some of my vacuum hoses are a little crummy, might as well replace those also while i am in there messing with hoses.

https://www.clubfrontier.org/threads/di ... ed.139449/
I've used this as a resource to preemptive replace batches of hoses on an Xterra, and I'm assembling the parts to do the Frontier also. For vacuum hoses, doing the PCV and the one that connects to it seem like the most important.