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#1
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Plug coolant bypass and drill hole in thermostat
Hey Guys,
I have tapped and plugged the small "coolant bypass" hole between the intake and the timing cover. I then experimented with 3 different size restrictors in place of a thermostat. Since I blocked the coolant bypass I cannot run a thermostat because the coolant has to go somewhere until the thermostat opens. Anyway, with all 3 restrictors my water temp never gets above 150 degrees. So tomorrow I want to experiment with drilling a small hole in a working 180 degree thermostat. The idea is that the hole will allow some coolant to flow through until the thermostat opens. ------- Well I tried drilling 3 x 1/4 inch holes in the thermostat and the engine still would not get up to temp, even with a 180 thermostat and only 3 little holes. I have 2 temp gauges installed, factory and aftermarket. So I know the gauges are right. Question. If I drill only 1 small 1/8 inch could this present a problem. I am concerned that if the thermostat is not open and the car is under load (5000 rpm) then to much pressure will build in the cooling system and "pop" something. The thermostat will not always be open and the engine could be at 170 degrees, if this happens will the high rpm and water pump cause the system to bust something? to much pressure? Is an 1/8 inch hole to small? John |
#2
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#3
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What problem are you trying to fix? I dont know what pressure the water pump can push, but its not much, 10-15 psi maybe. I think after that it would just bypass in the plate to impeller gap. I dont forsee it blowing any gaskets out. If your heater hoses are connected, its bypassing through the heater core anyhow.IMO ; )
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#4
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I always drill an 1/8th inch hole in all my thermostats to act like an air bleed. Done this on lots of cars-stock and performance- over 30+ years with not one issue.
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#5
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I have done the same in the last several years, for much the same reasons. I don't know if it helped.
I like your vid. We'll done. I enjoyed the systematic approach. Cooling systems always seem to work like constraint management. After you eliminate one constraint or cooling limiter, you uncover the next weakest link and have to start whacking on that one.
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"...ridge reamer and ring compressor? Do they have tools like that?" |
#6
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Good video.
I also add the air-bleed hole in the 'stat. |
#7
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A 1/8" hole is ok, nothing wrong with that. A lot of thermostats already have them, its called a "jiggle pin". Usually they are mounted horizontally with the pin at the top. Any more than that, and there is coolant going around the thermostat that it may not get hot enough to open. I would want the engine to be at
180f I think some people would put an aspirin on the thermostat to hold it open, after filling it, the aspirin would dissolve and the air was bled out. I would not do it on a newer (2000 and up) car. It may turn on a Check Engine light if the engine does not warm up fast enough. |
#8
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Can someone post a picture of a thermostat with the hole drilled in it?
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#9
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the high flow balanced sleeve type of stats like the Robert Shaw 330-xxx have an air bleed in them and an arrow indicating which way it should be installed, usually towards the front rad
it helps burp the system and acts a very small by pass without causing excessive cooling or reduced heating for those that need it http://static.summitracing.com/globa...0-195_w_ml.jpg here is one with some holes drilled in it http://static.summitracing.com/globa...p-300_cp_m.jpg |
#10
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Quote:
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#11
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SO,
The question I have is WHY would anyone block off the bypass? In the video he mentioned it is done for race cars and when it is a leaking problem, I have never had one leak on my Pontiac engines even when reusing an "O" ring. If you instal it correctly you won't have leaks. . |
#12
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Zim, Supercharger application...BDS recommends this procedure...I followed the advice from Craig Railsback....no problems...car runs at 160-170....all day.... ...IAII block...BDS 8 71 ...plenty of air flow...When we designed and built the car, myself and Richie Hoffman at Hoffman Racing did plenty of "thinking and worrying"...I was very concerned about cooling issues.... the car is an automatic, with A/C and power steering.....Eric
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#13
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Quote:
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#14
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Correction
The reason the bypass is blocked off has nothing to do with separating the water xover from the intake. The bypass can still be used [ or blocked ] whether the xover is stand alone or integral with the intake. The bypass serves two purposes: [1] it acts as pressure relief valve, should the stat jam in the closed position. [2] the bypass hole connects to the inlet side of the pump to heated coolant exiting the xover; the bypass gives faster warm up because some heated water is fed directly to the feed side of the pump. so really the only reason to block off the bypass is if the seal is leaking between the intake and the bypass. or in racing situations to change coolant flow using restrictors. I was unable to get the engine to come up to temperature no matter what type of hole I drilled in the thermostat with a blocked off bypass |
#15
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Quote:
I have drilled holes in the EDGE ring of the T-Stat to allow air to bleed past the t-stat and help filling the cooling system easier. I have installed bleeder type fittings in the water pump side of the timing cover to purge the air from the timing cover and help water pump efficiency. (Evans Cooling does this on all of their water pump modded vehicles). Without the bypass from the cross-over to the water pump side of the timing cover it is possible to cavitate the water pump under some conditions. Pontiac Engineers did Things for a Reason. Tom V. Some old aftermarket intakes did not have the provision for the by-pass to match up with the timing cover.
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"Engineers do stuff for reasons" Tom Vaught Despite small distractions, there are those who will go Forward, Learning, Sharing Knowledge, Doing what they can to help others move forward. |
#16
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My engine has an IAII block, an aftermarket timing cover, and E-brock water pump, and a Supercharger manifold from BDS...I blocked the by pass as per BDS's directions....Truth be told; I have no idea why it is recommended
I do therefore differ to the expertise and knowledge of the engineers...C.Railsback, T.Vaught, et al.....Whom I also thank for their patience, and information...Eric! |
#17
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I see many confused about the direction of flow of the block holes. The water flows out the stat, or when the stat is closed, circulates in the block/heads/core/pump areas.
So, if the cross-over bypass is blocked and the heater hose return to water pump Timing cover is blocked, and a thermostat installed, there will be no circulation in the block before thermostat opens? So then you have potential for the water pump cavitation. Thank you. What are your thoughts?
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68 Firebird. IA2 block, 505 cu in, SD Performance E-head, Solid roller 3600 weight. Reid TH400 4:11 gear. 29" slick. Best so far 9.95@134 mph. 1.43 60 ft. 76 Trans am, TKX .81 o/d, 3.73 Moser rearend, 468 with KRE D-ports, Doug headers, 3" Exh. |
#18
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Quote:
If the stat has opened a couple times in use, there is no, or very little air in the block/heads/core. The pump will just spin like a prop on a ship, water just won't go anywhere, and it won't 'cavitate'. Without air, you can't have cavitation. Technically, cavitation can only occur at the pump/pump housing. If the 'bypass', which is actually a 'bleed', is blocked, it could potentially prevent air from dissipating via the stat>rad. Where that air gets trapped is questionable, but without the bleed hole, it could potentially get trapped in the pump area. (And allow for cavitation). If you do block the bleed hole, and you've drilled a hole in the stat, it has a very similar effect as the bleed hole. But as some have mentioned, you may not reach full operating temp in use. And, it's possible air could get trapped in the pump housing area. That bleed hole is really to prevent air in the pump housing area. Not reaching temp is undesirable for emissions, and for removing moisture from the oil/engine. It could also prevent the heater from reaching full temps too. Stats don't slam shut or open fully instantly, that you need to keep in mind too. So in theory, even without the hole the air would bleed out to the rad. The only case that air MIGHT not bleed out the rad is if the rad cap is lower than the stat housing or is lower than the highest part of system. Even then, believe if eventually will bleed out. Coolant is under psi in operation, have to keep that thought too. If it weren't under psi, not only would the coolant boil at a lower temp, but you can have 'pockets' of air around high(er) temp areas, like the cyl and/or heads/chambers. Which brings up the 'Pontiac flow mods'. Some believe it's advantageous to reverse the flow of coolant and/or have the coldest coolant pass thru the heads first. To have efficient combustion, you have to have heat, so personally, believe the mod is worthless/counter productive. Just thinking out loud here... .
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. 1970 GTO Judge Tribute Pro-Tour Project 535 IA2 http://forums.maxperformanceinc.com/...d.php?t=760624 1971 Trans Am 463, 315cfm E-head Sniper XFlow EFI, TKO600 extreme, 9", GW suspension, Baer brakes, pro tour car https://forums.maxperformanceinc.com...ght=procharger Theme Song: http://www.youtube.com/watch?v=7zKAS...ature=youtu.be |
#19
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Awesome, Thanks for taking the time to reply.
__________________
68 Firebird. IA2 block, 505 cu in, SD Performance E-head, Solid roller 3600 weight. Reid TH400 4:11 gear. 29" slick. Best so far 9.95@134 mph. 1.43 60 ft. 76 Trans am, TKX .81 o/d, 3.73 Moser rearend, 468 with KRE D-ports, Doug headers, 3" Exh. |
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