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Complete TB Coolant line bypass

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Old Jan 16, 2007 | 04:02 PM
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Complete TB Coolant line bypass

Just wondering if anyone has taken the TB coolant line removal any further than just moving the line from the back of the TB to the connection just under it?

Coolant normally runs from the block connection near the firewall and close to the rear rotor oil injector, to the TB, then to the coolant line that is right by the fuel lines, which carries it along the front top of the motor and joins back to the water pump housing. If this was run straight from the rear connection to the water pump housing, then one could remove the hard line that is connected to the bracket for the fuel lines and clean things up a bit.

I'm not sure if there is enough clearance to the left of the rat's nest connections (looking from the front of the engine) for the line to run through. It would essentially run right above the secondary injectors and fuel rail, straight up to the termination. Since I'm bored and I want to work on something, I'll give it a shot and see if I can make things fit.

Anyone thinking of anything that I could have overlooked? There is an attachment point that goes from the hard line for the coolant to the rat's nest, but this doesn't hold the rat's nest in because it is attached to a bracket that screws down to the block.

Let me know what you guys think.

Jason
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Old Jan 16, 2007 | 05:08 PM
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From: next to the polishing wheel!!!
I plug the rear iron with a pipe plug and I remove the steel tube on the water pump house and some are threaded and pluged and some are welded closed ,which ever the customer wonts .I do not connect the two nipples with a rubber hose . A hose is a failure point . I make a cover plate for the throttle body to cover the holes where the hot wax rod was .
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Old Jan 16, 2007 | 05:12 PM
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From: Floyds Knobs. IN
Yes. The correct way to do it, if you have to, is to drill and tap the iron and water pump for plugs. Rubber plugs are certain failure.
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Old Jan 16, 2007 | 05:12 PM
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There was a thread about that ages ago. Some people in that thread were concerned about interrupting the flow of hot coolant by plugging that up. Others like GARCO above don't seem to have that concern.
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Old Jan 16, 2007 | 05:25 PM
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Originally Posted by GARCO MOTORWORKS
I plug the rear iron with a pipe plug and I remove the steel tube on the water pump house and some are threaded and pluged and some are welded closed ,which ever the customer wonts .I do not connect the two nipples with a rubber hose . A hose is a failure point . I make a cover plate for the throttle body to cover the holes where the hot wax rod was .
I see. That seems like it would work better than my cobbed idea. As far as the hose as another failure point, I don't think it's anymore than what was already there, because I used the existing hose. I loosened the clamp on the block end, and rotated it. It is just the right length.

I took some pics as I went along, so I will post those soon.

Thanks for the replies!

Jason
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Old Jan 16, 2007 | 05:48 PM
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From: Floyds Knobs. IN
Originally Posted by gracer7-rx7
There was a thread about that ages ago. Some people in that thread were concerned about interrupting the flow of hot coolant by plugging that up. Others like GARCO above don't seem to have that concern.

We do it on race engines all the time. It is NOT an issue. I have an engine in for overhaul right now that originally built by Speedsource. It's plugged in a similar manner.
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Old Jan 16, 2007 | 07:04 PM
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Mandeville plugged it on my motor.
Attached Thumbnails Complete TB Coolant line bypass-ccarlisi-mandeville-motor-2.jpg  
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Old Jan 16, 2007 | 07:30 PM
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I just joined the open hoses together with a barb fitting lol
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Old Jan 16, 2007 | 08:04 PM
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Pics as promised



And with everything mounted back on there:



I would love to tap and properly plug the holes, but I don't want shavings to get into the coolant and I think it would be a little difficult to get the one on the rear iron. Not even going to bother with rubber caps.

I didn't have any clearance problems to speak of, however I do not have the primary or secondary injectors in but the plugs for them seem to line up fine.

I'm getting good at this whole rat's nest removal/installation thing It is much less intimidating now, and I'm getting a basic understanding of how ***** routed.

Jason
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Old Jan 16, 2007 | 10:20 PM
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I've done a few different techniques on the many FC's I've worked on, and here's some of my findings -

Running the hose from the rear nipple to the water pump nipple will work, but the line has to be VERY well routed so it isn't pinched or rubbing on something. I've seen about 2 of these hoses fail on an FC when routed like that due to being pinched, but FC upper intake manifolds sit MUCH closer to the block than the FD's. If the line is routed well, that could work. For extra measure, I would put split loom tubing or something over the hose to prevent it from being chafed.

Using rubber vacuum caps is a HUGE no-no. The cheap ones from the auto parts store have NO business on an FD, period - not for vacuum caps, not for coolant, nothing. Now, for vacuum caps, I have used a high-temp rubber cap from McMaster-Carr that works great, but I wouldn't use it for coolant - the rubber has to be compatible with coolant and the pressure and heat it sees, and I doubt those caps are compatible.

However, one kinda ghetto but works great trick is to take the stock rubber hose, cut a short length, stick a bolt of appropriate size in one end and hose clamp that down, then hose clamp the hose "cap" on the nipple. Looks ghetto when you see it, but it holds up GREAT, far better than any cap.

Welding or tapping/plugging is the 100% best way to go. But, this usually isn't feasible without serious disassembly.

Personally, I run the coolant through the throttle body. The warmup feature works well, and I really don't think a warm throttle body is robbing me of that much horsepower. But, I can understand doing so if you're single turbo/no emissions and going "bare block".

Dale
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Old Jan 16, 2007 | 11:20 PM
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thanks for the info c ludwig and chris!
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Old Jan 17, 2007 | 05:07 AM
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From: next to the polishing wheel!!!
The throttle body is not heated with water only the hot wax rod , no water jacket around the throttle body .
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Old Jan 17, 2007 | 05:17 PM
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Originally Posted by GARCO MOTORWORKS
I plug the rear iron with a pipe plug and I remove the steel tube on the water pump house and some are threaded and pluged and some are welded closed ,which ever the customer wonts .I do not connect the two nipples with a rubber hose . A hose is a failure point . I make a cover plate for the throttle body to cover the holes where the hot wax rod was .


Like he said. I pull out the nipples and tap the rear iron 1/4" NPT and TIG weld shut the front one. No failures now...

tom
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Old Jul 2, 2008 | 10:22 AM
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Originally Posted by edwin-82/rx7
Pics as promised

I would love to tap and properly plug the holes, but I don't want shavings to get into the coolant and I think it would be a little difficult to get the one on the rear iron. Not even going to bother with rubber caps.

Jason
I feel the same way. I takr my 13b down to the keg frequently, but i havn't pulled the irons apart yet (and don't relly want to at the moment).
would drilling/ tapping the rear iron be feasibly with the keg assembled? i mean concerning getting debris into the cooling system?

i guess one could just flush it out by putting a garden hose up agains the water pump inlet and ghetto sealing it on there with your hand/ a rag. does that sound like it would clean everything out reasonably well? anyone else have any good techniques for flushing the coolant?
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Old Jul 2, 2008 | 08:06 PM
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so if you just take pilers and plug at those steel nipples they'll come right out?
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Old Jul 5, 2008 | 06:09 PM
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From: Floyds Knobs. IN
Originally Posted by scrubolio
so if you just take pilers and plug at those steel nipples they'll come right out?

I doubt it. Never tried though. I always take a cutoff wheel and cut them off flush. Then chuck up a 7/16" bit and drill them out. The 7/16" bit is the right size for the 1/4" NPT tap so it works out perfectly.
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Old Jul 5, 2008 | 08:30 PM
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i just run a coolant hose from the back to the waterpump area... problem solved for under 5.00
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Old Feb 9, 2026 | 11:10 PM
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Originally Posted by grimple1
i just run a coolant hose from the back to the waterpump area... problem solved for under 5.00
I am planning on doing this and delete the hardline. Does this mean I need to secure the thermowax and then plug the two holes in the TB for the coolant hoses?
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Old Feb 10, 2026 | 09:33 AM
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Originally Posted by supertonggi
I am planning on doing this and delete the hardline. Does this mean I need to secure the thermowax and then plug the two holes in the TB for the coolant hoses?
You do not need to plug the nipples on the throttle body since there will be no coolant in it. I suggest you remove the thermowax entirely.
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Old Feb 10, 2026 | 11:57 AM
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Originally Posted by Cgotto6
You do not need to plug the nipples on the throttle body since there will be no coolant in it. I suggest you remove the thermowax entirely.
I ended up removing the spring on the screw as recommended and tighten screw all the way down. I need to review what exactly the entire thermowax consists of so I can do it. I plugged the coolant hoses just so I know it's not used.
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