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I have a question about 3.4 DOHC coolant hardlines... by 268 GT
Started on: 01-13-2011 08:32 AM
Replies: 16
Last post by: 268 GT on 01-19-2011 12:10 PM
268 GT
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Report this Post01-13-2011 08:32 AM Click Here to See the Profile for 268 GTSend a Private Message to 268 GTDirect Link to This Post
I believe these are for the heater core but I'm not positive.






I 'T'ed into the heater line for the Fiero from the outlet coming off the backside of the water pump on the DOHC and bypassed that metal hardline. I plan to cut the hardlines and weld them shut and re-install and slip a cap over the coolant fitting to the right coming out of the lower intake manifold. Does anyone see a problem with my methods other than looking like crap? This is a project/track car that needs to see the track on the 22nd so time is running out.

Thank you.


Robert

------------------
Power is nothing without control.


Twin Engine Fiero Project

1987 Checkmate Starflite
1988 Fiero GT 3.4 DOHC
1990 Miata
1991 300ZX Twin Turbo
1997 F355 Berlinetta
1999 ex-CART FedEx Championship Series racecar
2000 Civic Si
2000 F-250 PSD 6-speed
2005 YZF-R1
2005 United 24ft enclosed hauler

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tesmith66
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Report this Post01-13-2011 12:16 PM Click Here to See the Profile for tesmith66Send a Private Message to tesmith66Direct Link to This Post
I think that's part of the bypass system and is necessary. I wanted to block off the TB passage and do away with that line, but have since learned that the system bypass is through the TB and is necessary. I will be running a heater core, though. I don't know if a bypass is necessary without a heater.

Hope this helps...?

I think it would be a good idea to wait for the smarter kids to chime in before you cut anything...

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1986 SE 350 V8

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268 GT
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Report this Post01-13-2011 12:21 PM Click Here to See the Profile for 268 GTSend a Private Message to 268 GTDirect Link to This Post
Agreed, I won't make any permanent modifications until I find out for sure.

Thank you.

[This message has been edited by 268 GT (edited 01-13-2011).]

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268 GT
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Report this Post01-14-2011 10:39 AM Click Here to See the Profile for 268 GTSend a Private Message to 268 GTDirect Link to This Post
Does anyone have an answer? I'd like to test the coolant system for leaks this weekend.


Robert
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1fatcat
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Report this Post01-14-2011 12:06 PM Click Here to See the Profile for 1fatcatSend a Private Message to 1fatcatDirect Link to This Post
Almost all engines use the bypass to circulate coolant in the block & heads when the thermostat is closed. Without a bypass, the coolant has no circulation in the engine when the stat is closed. This results in the cylinder head temperatures skyrocketing before the hot coolant can get to the stat and open it. Once the stat opens, circulation starts again.

Most of the heat generated in an engine is generated in the cylinder heads, not so much in the cylinder water jackets.

Because the stat is in the intake manifold, where little to no heat is made, the hot coolant needs to be circulated in the engine to be moved from the heads to the stat. Please keep in mind that the radiator is taken out of the equation when the stat is closed. We're talking about circulation in the engine only.

That being said, I would not recommend blocking off the bypass. HOWEVER, if you are running a hallowed out stat, or a fixed size opening in place of the stat, or no stat at all, THEN you could block off the bypass.

Edit: The bypass pipes do feed the heater core, but the heater core is part of the bypass system. You can still have a functioning bypass without a heater core, but you need to loop the bypass where it would have gone into the heater core to where it would have come out of the heater core. So basically, you just substitute the heater core with a piece of hose.

[This message has been edited by 1fatcat (edited 01-14-2011).]

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268 GT
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Report this Post01-14-2011 03:12 PM Click Here to See the Profile for 268 GTSend a Private Message to 268 GTDirect Link to This Post
Thank you for the explanation. I thought I found a way to simplify the plumbing but I will put it back.
Can I still cap off the large fitting on the right coming out of the lower manifold? I already have the other end of the heater core connected on the Fiero coolant pipe.

I have another question regarding a hardline that runs under the lower manifold between the heads. I don't know where that goes or what it carries (coolant or ?). I will get a picture tonight.


Thanks guys.
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86blackgt
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Report this Post01-14-2011 11:05 PM Click Here to See the Profile for 86blackgtSend a Private Message to 86blackgtDirect Link to This Post
t

[This message has been edited by 86blackgt (edited 01-14-2011).]

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268 GT
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Report this Post01-15-2011 11:26 AM Click Here to See the Profile for 268 GTSend a Private Message to 268 GTDirect Link to This Post
Ok it looks like the smaller hardline under the lower intake manifold is a crankcase breather.

As for the coolant fittings on the lower manifold; I want to cap off the metal tube and run the heater hose from the pressed in fitting. I will reinstall the black hardline (bypass) but cap the open fitting.


Rob
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qwikgta
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Report this Post01-15-2011 11:40 PM Click Here to See the Profile for qwikgtaSend a Private Message to qwikgtaDirect Link to This Post
On your first question about the coolant tube, I cut off the smaller section that turn off the main line, and put a rubber "cap" on it. Its not needed. In our system, the return line from the heater box taps into the main coolant line at the back of the passenger side "main" tube, so you don't have to connect it to the heater. It least thats what I did. The larger section does need to go into the intake mani, you do need to complete that part of the system.

The hardline is for the crankcase evep system. It should feed into the upper intake below where the TB attach's to the Intake






In this picture i have a oil seperator placed in between the intake and the hardline, but you can see in the picture where it attach's to the intake just below the TB arm.

Rob

[This message has been edited by qwikgta (edited 01-16-2011).]

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268 GT
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Report this Post01-16-2011 11:56 AM Click Here to See the Profile for 268 GTSend a Private Message to 268 GTDirect Link to This Post
Perfect, exactly the explanation I needed. Thank you

Rob
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Report this Post01-17-2011 12:48 AM Click Here to See the Profile for 1fatcatSend a Private Message to 1fatcatDirect Link to This Post
never mind

[This message has been edited by 1fatcat (edited 01-17-2011).]

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268 GT
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Report this Post01-17-2011 07:24 PM Click Here to See the Profile for 268 GTSend a Private Message to 268 GTDirect Link to This Post
So if I connect A to B and cap off C should I be good to go?




Rob
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qwikgta
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Report this Post01-17-2011 11:22 PM Click Here to See the Profile for qwikgtaSend a Private Message to qwikgtaDirect Link to This Post
Some of this is obvious and i appoligize in advance if you know this. Our cars have two lines runningn into/out of the heater box. One runs to the motor the other "T's" into the system under the passenger seat. Because of this, we only have one hose going to the motor, but the 3.4 DOHC motor has the two fittings, becuase in the cars that the motor was in, they had both hose's running to the motor. So we have to cap one of the fittings and utilze just the one. I don't recall off the top of my head which one, but im sure someone here knows. That being said, its tough to see with that pic which hose your "A" is. If its the heater line, I would not have it so high. I had mine parallel to the motor on the back firewall.

In my car, as I recall, off the waterpump is the tube you have in your first pic. I capped "B". On my car, I had a coolant hose going into your "C". I ran it across the back of the fire wall, and had it loop around and go into your "C". It may be your "A" above, but agian im not sure. On the second pic a sent in an earler post, you can see what I plumed into "C". Its the hose that runs parallel with the power brake booster hose that runs into the TB Arm.

I don't have a good pic, because it was all hidden under the TB arm. But i'll include what I have. in my system, I did't use the hardline in your pic, because of the headers, I needed to move it up a little and used a piece of heater hose.

Don't pay attention to the fuel lines, I had to place them up so that fuel didn't continue to drip, they were not mounted like that.








rob

[This message has been edited by qwikgta (edited 01-17-2011).]

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tesmith66
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Report this Post01-18-2011 06:14 AM Click Here to See the Profile for tesmith66Send a Private Message to tesmith66Direct Link to This Post
 
quote
Originally posted by 268 GT:

So if I connect A to B and cap off C should I be good to go?




Rob


OK, I see 2 TB's, a large plenum and exhaust in weird places. What are you up to?

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1986 SE 350 V8

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268 GT
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Report this Post01-18-2011 08:24 PM Click Here to See the Profile for 268 GTSend a Private Message to 268 GTDirect Link to This Post
.....oh nothing, hehe

'96 DOHC, long-tube headers, large dual TB plenum, aggressive retard on cams, etc etc. As for the car; completely gutted, Sparco race seats, cage.......

I'll make a build thread in the General once it's finished.
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Report this Post01-18-2011 08:38 PM Click Here to See the Profile for L67Send a Private Message to L67Direct Link to This Post
Been a while since we've heard from you. The video of your garage burning down still haunts me.
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268 GT
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Report this Post01-19-2011 12:10 PM Click Here to See the Profile for 268 GTSend a Private Message to 268 GTDirect Link to This Post
That was the worst weekend of my life, the fire Saturday night and losing a close friend Sunday afternoon.

I've been busy with other projects but I haven't forgotten my roots. Working on this project is like going back in time for me. It will feel wonderful to drive this car again after 8 years. This is the second car I bought (first was an '86 GT 4-speed) so it has a lot of sentimental value.

It's good to be back.


Rob

------------------
Power is nothing without control.


Twin Engine Fiero Project

1987 Checkmate Starflite
1988 Fiero GT 3.4 DOHC
1990 Miata
1991 300ZX Twin Turbo
1997 F355 Berlinetta
1999 ex-CART FedEx Championship Series racecar
2000 Civic Si
2000 F-250 PSD 6-speed
2005 YZF-R1
2005 United 24ft enclosed hauler

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