Rear coolant hoses

[tmorgan4]

Hey everyone,

I'm back.....and it's time to do some more engine work. I disappeared for a little while as I was focusing on other parts of my project but now that it's time to figure out a few engine issues I'm back where the experts are. I apologize greatly to everyone who emailed me about the Mazworx adapter. I started doing too many things at once and I'm not going to attempt the TH400 swap quite yet.

I'm pulling out my engine again and fixing a few issues that I've been regretting every since I put the engine together. Most of them are dealing with the cooling system. I put rubber caps on some of the coolant lines (like capping off the small lines that are supposed to run to the throttle body) and I've been advised that these are going to crack eventually and leave me stranded at the worst possible time.

I also managed to crack the two rear hoses that run off the back of the head/through the valley to the heater core since they were pushed up against the firewall. Fortunately it didn't happen while the engine was running, but I need to do something about it.

I've been looking into installing AN fittings on both the head and the small tube next to it and running 90* fittings with a high quality hose to keep it from making a sharp turn right before the firewall. I'm running into issues finding a -20 AN fitting that is acceptable for this purpose and I'd really like to find a -20 to a -20 hose barb but I'm not sure they exist.

I just saw some pictures of Dixon's engine that I've got saved on my computer and it looks like he may have done something similar.

Anyone else done this?

[gs14racer]

Ive done a lot of an lines but im trying to visualize which hoses exactly you are talking about. Got pics?

[tmorgan4]

I was just about to look up your build and see if you happened to do these....Glad to see you're still around here, too.

I'm talking about the two bigger coolant lines that run up to my heater core on the far left. One comes out of the back of the head and other runs through the valley.

With the cheap rubber parts store coolant hose I've got it comes straight out the back and has to make a sudden turn before the firewall which ended up cracking them.

[gs14racer]

I was just about to look up your build and see if you happened to do these....Glad to see you're still around here, too.

I'm talking about the two bigger coolant lines that run up to my heater core on the far left. One comes out of the back of the head and other runs through the valley.

With the cheap rubber parts store coolant hose I've got it comes straight out the back and has to make a sudden turn before the firewall which ended up cracking them.

Yea im still one here , typically every day although i dont post much.

Well on mine i plugged all that stuff up since no heater was required ( miami weather negates the heater ) . But you could well an steel bungs on those peices and use hose and fittings but -20 would be way to big it would be more like -10 or -12.

[T45]

I beg to differ. It was in the high 30's the other night Jerry. lol Wazup Tmo!

[gs14racer]

Yea it was like air conditioning. However its like that 8 times a year heater weighs like 10lbs weight reduction lol....

[maxnix]

With the cheap rubber parts store coolant hose I've got it comes straight out the back and has to make a sudden turn before the firewall which ended up cracking them.

I With the cheap rubber parts store coolant hose I've got it comes straight out the back and has to make a sudden turn before the firewall which ended up cracking them.

Nice cleaning job.

Guess I am missing what is wrong with OEM.

[SuperHatch]

Hey everyone,

I'm back.....and it's time to do some more engine work. I disappeared for a little while as I was focusing on other parts of my project but now that it's time to figure out a few engine issues I'm back where the experts are. I apologize greatly to everyone who emailed me about the Mazworx adapter. I started doing too many things at once and I'm not going to attempt the TH400 swap quite yet.

No worries on the adaptor. Just glad to see you're back!

I'm pulling out my engine again and fixing a few issues that I've been regretting every since I put the engine together. Most of them are dealing with the cooling system. I put rubber caps on some of the coolant lines (like capping off the small lines that are supposed to run to the throttle body) and I've been advised that these are going to crack eventually and leave me stranded at the worst possible time.

Make sure you actually run these lines to the throttle body. On most cars these serve to warm the throttle chamber and prevent freezing of the throttle plate in cold weather. On the VH, it no only does this, but it also warms up the FIAV (Fast Idle Air Valve) which is normally open until the wax pellet gets hot and closes the orifice. Of you leave this open, the wax will never expand and you will have a high idle. You can adjust the throttle plate to close more (makes it possible for the plate to stick closed) and adjust the idle screw on the IACV, but you might run into stalling issues when cold.

I also managed to crack the two rear hoses that run off the back of the head/through the valley to the heater core since they were pushed up against the firewall. Fortunately it didn't happen while the engine was running, but I need to do something about it.

I used pre-formed heater core hose from autozone that had 90* bends on my Z. (My S14 doesn't have heat)





If you notice I have some brass transitions converting the 3/4" VH output to the 5/8" Z32 heater core size. I bought these fittings from Lowes for $5. The 90* hoses were $7 each at most. The upper hose has a 3/4" "T"-Fitting with a 5/8" Branch. The 5/8" branch goes to the other heater core port and the 3/4" hose running to the left goes to my surge tank.

Just a cheaper option than going AN if you're un a budget. An AN fitting might be a slightly tighter radius than this, I don't know how little space you have.

Also, the heater core on a Z is equivalent to -10 and the outlets on the VH are -12 if you needed to know.

[tmorgan4]

I beg to differ. It was in the high 30's the other night Jerry. lol Wazup Tmo!

You get your whip running again yet!??

[tmorgan4]

Yea im still one here , typically every day although i dont post much.

Well on mine i plugged all that stuff up since no heater was required ( miami weather negates the heater ) . But you could well an steel bungs on those peices and use hose and fittings but -20 would be way to big it would be more like -10 or -12.

Thanks Jerry. I'm really glad to hear I don't need some -20 90* AN fittings since I found them on Summit at @ $90 apiece.

I looked back through some posts on here and found someone mention that the heater hoses were 1.25" diameter which would be a -20 hose. Maybe I read it wrong since a -12 (3/4") sounds much more reasonable.

[tmorgan4]

Nice cleaning job.

Guess I am missing what is wrong with OEM.

Thanks for the kind words. Basically the OEM hoses won't work because I have so little room between the firewall and the back of the engine. I built the engine mounts to make the engine sit as far back as possible for suspension clearance and to try and move some weight towards the rear.

[tmorgan4]

No worries on the adaptor. Just glad to see you're back!

Make sure you actually run these lines to the throttle body. On most cars these serve to warm the throttle chamber and prevent freezing of the throttle plate in cold weather. On the VH, it no only does this, but it also warms up the FIAV (Fast Idle Air Valve) which is normally open until the wax pellet gets hot and closes the orifice. Of you leave this open, the wax will never expand and you will have a high idle. You can adjust the throttle plate to close more (makes it possible for the plate to stick closed) and adjust the idle screw on the IACV, but you might run into stalling issues when cold.

I used pre-formed heater core hose from autozone that had 90* bends on my Z. (My S14 doesn't have heat)

If you notice I have some brass transitions converting the 3/4" VH output to the 5/8" Z32 heater core size. I bought these fittings from Lowes for $5. The 90* hoses were $7 each at most. The upper hose has a 3/4" "T"-Fitting with a 5/8" Branch. The 5/8" branch goes to the other heater core port and the 3/4" hose running to the left goes to my surge tank.

Just a cheaper option than going AN if you're un a budget. An AN fitting might be a slightly tighter radius than this, I don't know how little space you have.

Also, the heater core on a Z is equivalent to -10 and the outlets on the VH are -12 if you needed to know.

Thanks for the warm welcome.

Of course I'm always on a budget but I just want to do things right. I already did this wrong once so my second attempt better work!

I'm trying to judge how much more room you've got to fit hoses back there by the firewall than I do. I do remember than I can hardly fit my hand in between the IACV and the firewall on mine.

Good point on the throttle body lines. I had looked over that and basically just capped them off like you can see in the picture. In my case a high idle really isn't a bad thing (running a big power steering pump, harder to stall) so I may need to play with the IACV valve. I bet that wax pellet won't ever get up to temp without hot coolant running through it.

I found some really tight radius silicone 90* hoses but by the time I buy a few $50 elbows I might as well get some AN fittings and lines.

Appreciate the feedback from everyone!!!

[darinz]

I just searched through the oem hoses at the local parts place and found ones that had the right bend fromed into them. Really simple, cheap and easy.I haven't worried about any coolant hoses going to the TB and have had no issues with idle or cold starting and that includes a trip to Rotorua where it was below 0*C. I'm not running fastory ecu so that does make a fair bit of diffirence though.

[SuperHatch]

I just searched through the oem hoses at the local parts place and found ones that had the right bend fromed into them. Really simple, cheap and easy.I haven't worried about any coolant hoses going to the TB and have had no issues with idle or cold starting and that includes a trip to Rotorua where it was below 0*C. I'm not running fastory ecu so that does make a fair bit of diffirence though.

I don't run the TB coolant lines on my S14, and it had an unusually high idle when I got it running. I was able to adjust it down with the throttle plate adjustment and the IACV set screw.

On my Z I did run the lines, I didn't need to adjust a single thing to get it to idle right. Worked perfect from the get go...

Those are my experiences. I bet your standalone was a big part on how well your car idles.

[gs14racer]

Well i dont have the tb lines or an iac valve on this motor or the last, and just adjusting the throttle plate i was able to get rock solid idle 850 rpm but then again we dont have real big temperature swings here where im at lol.

The only problem i ever had was when i first got it running there was no filter and when the fan would come on the idle would go crazy but i attributed that to turbulence in front of the maf by the fan.

[maxnix]

Well i dont have the tb lines or an iac valve on this motor or the last, and just adjusting the throttle plate i was able to get rock solid idle 850 rpm but then again we dont have real big temperature swings here where im at lol.

IAC mostly adjusts for accessories power drain. Don't see why you wouldn't want to leave it and have the 625-650 rpm in street driving. Unless you are not.

[T45]

I'm still working on it, trying to decide what in the hell to do with it.

As for AN lines, just find a local hose shop and they'll build you whatever you like. I guarantee it will be cheaper than the Summit re-usable fittings and will be much stronger as well. Re-usables are ok, but you can have custom lines crimped for less than half the price of the anodized "race" fittings.

[SuperHatch]

I'm still working on it, trying to decide what in the hell to do with it.

As for AN lines, just find a local hose shop and they'll build you whatever you like. I guarantee it will be cheaper than the Summit re-usable fittings and will be much stronger as well. Re-usables are ok, but you can have custom lines crimped for less than half the price of the anodized "race" fittings.

Agreed... BTW, I got your email and I'm not ignoring you. Just need to get some ducks in order before I can give you a definitive response.

[T45]

No sweat, I kinda figurred. Thanks.

[Mettler]

tmorgan4 I have the same issue as you, but my motor sits so close to the firewall that I couldn't even use preformed 90 deg hose bends... I'm gonna need to make up some custom steel fittings or something to do that. I had my workmate turn up some reducer hosetail fittings from stainless to go from the larger size hose down to the smaller size for my heater inlet & outlet.

IAC mostly adjusts for accessories power drain. Don't see why you wouldn't want to leave it and have the 625-650 rpm in street driving. Unless you are not.

I haven't seen much of a trend in favour of leaving things OEM in this subforum

[Raxephon]

Has anyone cut the original pipe off the back of the left bank cylinder head, tapped it, and installed a 90 DEG -an fitting?

The line that runs across the top of the block to the main coolant junction can just be shortened and flared.

[tmorgan4]

Has anyone cut the original pipe off the back of the left bank cylinder head, tapped it, and installed a 90 DEG -an fitting?

The line that runs across the top of the block to the main coolant junction can just be shortened and flared.

This is EXACTLY my plan. I'm hoping I can just tap it and install a fitting since it would be the ideal way of getting it flush with the head. If it's welded on, a little bit of the pipe coming off the head is going to have to remain and I'm not sure whether it will be accessible (to be welded to) without removing the head. I just put these damn things on so it would be nice to not have to pull the head and replace the gaskets and bolts.

I don't have my engine out of the Pathfinder yet to check sizes but I'm hoping it's closes enough to a standard NPT size that it can be tapped.

Like you mentioned, the other tube can just be shortened.

[darinz]

Tell us what you do tapping a 90* in will make mine much tidier so I'll like to know the outcome.

Also mine idles at about 650 and even thermo fans etc cutting in don't effect it. No IAC etc just a very good ecu that does what it is supposed to do. Costs a bit more but we are talking afew hundred dollars when a cheap crap one is NZ$1800. It amazes me how many people try and save a few dollars but it ends up costing more in the long run. Do it once do it right is often a lot cheaper!

[tmorgan4]

Finally got my engine pulled this past weekend. I'm going to go through the whole thing over the next couple weeks and re-do all the parts I wasn't happy with.

I'm going to try and document everything well since I think it would work great for a lot of other people. This picture shows exactly what happened with my rear coolant hoses and why I'm having problems. I initially tried installing the coils around the hoses to keep them from kinking but they didn't work. The hoses eventually cracked.

I'll start a new thread on this soon.

[tmorgan4]

SUCCESS!!!!

Please excuse my ugly engine. I don't know how it got so dirty!!

[darinz]

SUCCESS!!!!

Please excuse my ugly engine. I don't know how it got so dirty!!

You're s***ting me aren't you! That motor is in show room condition compared to mine!!!!!!!!!!

[Steve Lloyd]

SUCCESS!!!!

Can you explain what you did here?? I want to do something similar and don't have a way to get anything welded on. What size Tap/fitting did you use??

Thanks..........

[piranhamatt]

Wow, I'm really liking this idea. Thanks for posting that!

[tmorgan4]

Sorry, didn't see this until now!! I'll look up the parts I bought to make sure I give you correct info....It has been awhile.

[Steve Lloyd]

Sorry, didn't see this until now!! I'll look up the parts I bought to make sure I give you correct info....It has been awhile.

No problem, I just thought I would bump this instead of starting a new one since someone else actually did what I want to do.

Any help is great, or at least a process so I know what I'm in for............

Steve