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rate of pressure rising in cooling system on revving


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TheGrinder(ofgears)
User

Nov 7, 2021, 4:00 PM

Post #1 of 10 (346 views)
rate of pressure rising in cooling system on revving Sign In

Salem Boys Auto's website says "Apply pressure to the cooling system and watch the pressure gauge as you rev the engine. If the pressure rises quickly, that is a very good indication there is a combustion leak."

how fast is "quickly"? i did this test and the results are in the video below. did the pressure rise "quickly"?

https://youtu.be/KnbwuQ4QxA4


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Nov 7, 2021, 5:04 PM

Post #2 of 10 (342 views)
Re: rate of pressure rising in cooling system on revving Sign In

Not really. The rise in temp alone along with the cavitation of the pump will increase the pressure so he's wrong about that.

Some techs will tie a latex glove with a tight seal at the filler and see if the glove inflates. That's not really foolproof either though.

The only true test of combustion gases in the cooling system is to sniff at the radiator cap with an exhaust analyzer while the engine is running and it will read hydrocarbons in the coolant.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



(This post was edited by Hammer Time on Nov 7, 2021, 5:05 PM)


TheGrinder(ofgears)
User

Nov 7, 2021, 5:12 PM

Post #3 of 10 (336 views)
Re: rate of pressure rising in cooling system on revving Sign In

is a block tester kit with the blue fluid that turns yellow as reliable as the exhaust analyzer?


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Nov 7, 2021, 5:15 PM

Post #4 of 10 (334 views)
Re: rate of pressure rising in cooling system on revving Sign In

Nowhere near. It has to be a really bad leak to get a positive test from one of those. If it's bad enough for that to find it, then it's usually pouring white smoke out the back and obvious.

Another trick is to remove all the spark plugs and apply coolant pressure with a pressure tester for at least 30 minutes. Then crank the engine with the plugs out and see if it spits any coolant out any of the cylinders.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



(This post was edited by Hammer Time on Nov 7, 2021, 5:18 PM)


TheGrinder(ofgears)
User

Nov 7, 2021, 5:17 PM

Post #5 of 10 (328 views)
Re: rate of pressure rising in cooling system on revving Sign In

hmm...another expensive tool to buy...argh.


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Nov 7, 2021, 5:19 PM

Post #6 of 10 (324 views)
Re: rate of pressure rising in cooling system on revving Sign In

A cooling system pressure tester is a commonly used tool. You might be able to rent or borrow one from Autozone.

Yep, it's expensive to fix cars.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



(This post was edited by Hammer Time on Nov 7, 2021, 5:21 PM)


TheGrinder(ofgears)
User

Nov 7, 2021, 5:51 PM

Post #7 of 10 (318 views)
Re: rate of pressure rising in cooling system on revving Sign In

i have one. it is the exhaust gas analyzer that i was referring to.


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Nov 7, 2021, 5:56 PM

Post #8 of 10 (316 views)
Re: rate of pressure rising in cooling system on revving Sign In

Forget that. You ain't buying one of them. You're talking thousands of dollars. If you want that test then you just pay a shop to do it.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



TheGrinder(ofgears)
User

Nov 7, 2021, 6:58 PM

Post #9 of 10 (304 views)
Re: rate of pressure rising in cooling system on revving Sign In

based on the way the gauge is moving in the video, i'm guessing the glove would inflate, though it probably wouldn't stay that way. i'm guessing it would retract like the gauge does.

is it how inflated it STAYS after the engine stops revving that is important? because i'd think the exhaust gasses would create more permanent movements upward in pressure when the revving subsides.


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Nov 7, 2021, 10:34 PM

Post #10 of 10 (289 views)
Re: rate of pressure rising in cooling system on revving Sign In

Grinder > Careful with videos IMO can be and are plain wrong or wrong for your needs for repairs, it's just not your exact scene or corrupted to see you even watched it!
Tools expensive goes with this trade and others love it or it's not for you.
These pressure testing things with an engine. OMG, not with them running - just don't. Pressure from heat and water pump's work in play you wreck something that wasn't broken locking in pressure as mine does, old but is also why it works! STANT's kit. No joke, from the 70's works as new still it's all brass parts not junk seen now. Snap-On would still have the superior things also with a mortgage to buy it.


I need some adaptors for more assorted pressure caps just haven't gone out on the hunt yet.


That locks pressure you leave and look at it like Hammer said 1/2 hour later, plugs out if chasing a leak in head gaskets if that's the reason for checking.
Handy when no coolant in a system use soapy water (cold engines) see how it hold air if so it will hold liquids.
Rubber glove? Amusing but not so helpful IMO most you can just feel the largest hose build pressure normal as it warms up, not normal if already warmed up and rebuilds pressure right away again - duh - careful you take off a pressure cap while it was hot so know how to do that without being the next burn victim and when to not proceed it's too hot, More tool$.
Exhaust testing things: I've been pre-warned they are not very conclusive so no more comment I don't use those at all.


Wrong info is worse than no info - trust me on that!


Tom







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