Recent Topics
They don't make 'em like they used to...
by Alex_V
04/21/18 06:55 PM
5W-20 P.U.P. at Walmart (yes, in stock!) $24.97
by Linctex
04/21/18 06:37 PM
Havoline ProDS 10w30 on Rollback at Walmart
by JohnnyJohnson
04/21/18 05:43 PM
Richmond Raceway
by Warstud
04/21/18 05:40 PM
2009 Mustang GT
by GMFan
04/21/18 05:22 PM
Is your A/C ready for the summer?
by Nick1994
04/21/18 04:51 PM
Pennzoil Synthetic Rollback Walmart
by FordBroncoVWJeta
04/21/18 04:48 PM
Alternators, A just in case Scenario.
by rollinpete
04/21/18 04:38 PM
Palm Ratchets
by 2015_PSD
04/21/18 04:32 PM
2013 Equinox ATF change
by Dave Sherman
04/21/18 04:13 PM
Champion vs NGK Spark Plugs ?? Iridium
by fins
04/21/18 03:46 PM
Are you driving the same car since 2010
by CourierDriver
04/21/18 03:45 PM
2018 Diesel F150
by BlueOvalFitter
04/21/18 03:09 PM
Do I really need iridium spark plugs?
by cheesepuffs
04/21/18 03:06 PM
Any wing lovers here?
by car51
04/21/18 03:03 PM
C&P Hastings LF240 @ 10,000 miles - 96 Maxima
by 92saturnsl2
04/21/18 03:02 PM
FULL brand oil filter UN USED CUT OPEN
by car51
04/21/18 02:27 PM
So how much do you pay for gas?
by rollinpete
04/21/18 02:10 PM
Adjusting Alternator Voltage
by George7941
04/21/18 01:48 PM
what if i dont know what to use
by VTAK
04/21/18 01:41 PM
Newest Members
Marc32275Jax, puma4440, zeroyon223, wade12345, rdatman
64806 Registered Users
Who's Online
107 registered (bbhero, Ag76, ATex7239, AEHaas, 2015_PSD, ArrestMeRedZ, 10 invisible), 1464 Guests and 38 Spiders online.
Key: Admin, Global Mod, Mod
Forum Stats
64806 Members
68 Forums
282086 Topics
4709615 Posts

Max Online: 3590 @ 01/24/17 08:07 PM
Donate to BITOG
Topic Options
#4692257 - 03/12/18 09:01 AM Cooling system leak / pressure test question
mrdctaylor Offline


Registered: 06/05/03
Posts: 528
Loc: McGregor TX
Hey guys,

I've had a coolant leak in my son's 2003 Santa Fe for months. The reservoir goes from the full line down to below the low line in around a month. There was never any evidence of it being in the oil and it wasn't a fast enough leak to make it to the ground and pool up. A couple of months ago, I took it in and my mechanic did a pressure test and couldn't find anything. He said it held pressure over night. He replaced one hose clamp where there were a few drops of coolant, but other than that he couldn't find anything. Fast forward to a couple of weeks ago. I took it back in because it was still losing coolant regularly. This time he drove it around and got it good and hot before putting it on the lift, since a pressure test hadn't shown anything previously. This time he could see some coolant leaking from the water pump. Fortunately for me, this was still under warranty because he'd had to replace it this past summer when the original water pump went belly up. I guess we just got a bad pump since it had pretty much had a coolant leak since then--we just didn't realize it immediately. It looks like that finally solved the leak.

So my question is this: Why would this leak not show up under a pressure test? Why would it only start leaking when hot? I mean, it sort of makes sense, but I just like to understand exactly what's going on with my vehicles so I'll know what my mechanic is talking about.

Thanks in advance!
_________________________
12 Highlander 3.5L, 84K, M1 EP 0W20
02 Tacoma 3.4L, 211K, Napa Syn 5W30
17 Escape 2.0L, 28K, ???
02 Trailblazer 4.2L, 174K, Magnatec 5W30

Top
#4692271 - 03/12/18 09:13 AM Re: Cooling system leak / pressure test question [Re: mrdctaylor]
Billbert Offline


Registered: 10/09/09
Posts: 342
Loc: California
Nearly everything expands when heated, different materials expand at different rates and clearances change. Could have been a tolerance stack up problem.
_________________________
If you think you can, or if you think you can't, You are probably right.

Auto Instructor / ASE Master Tech

Top
#4692273 - 03/12/18 09:15 AM Re: Cooling system leak / pressure test question [Re: Billbert]
mrdctaylor Offline


Registered: 06/05/03
Posts: 528
Loc: McGregor TX
Originally Posted By: Billbert
Nearly everything expands when heated, different materials expand at different rates and clearances change. Could have been a tolerance stack up problem.


Right. That's my thinking. But by the same token, a pressure test seems to be THE test for cooling systems. Maybe that's a misunderstanding on my part. Unfortunately, at least in some cases it gives a false reassurance that there is no issue. :-/
_________________________
12 Highlander 3.5L, 84K, M1 EP 0W20
02 Tacoma 3.4L, 211K, Napa Syn 5W30
17 Escape 2.0L, 28K, ???
02 Trailblazer 4.2L, 174K, Magnatec 5W30

Top
#4692274 - 03/12/18 09:15 AM Re: Cooling system leak / pressure test question [Re: Billbert]
Trav Offline


Registered: 11/20/06
Posts: 18234
Loc: MA, Mittelfranken.de
+1 heat expansion.
_________________________
ASE L1, Master. Deutsch Meisterbrief.

Top
#4692335 - 03/12/18 10:42 AM Re: Cooling system leak / pressure test question [Re: mrdctaylor]
LeakySeals Offline


Registered: 02/18/11
Posts: 6514
Loc: Hudson, NH
AKA Expansion tank.
_________________________
06 Escalade 6.0L AWD 155k. M1 EP 5w30 Fram TG
03 Maxima 3.5L Unknown miles ST 10w30

Top
#4692339 - 03/12/18 10:51 AM Re: Cooling system leak / pressure test question [Re: mrdctaylor]
bullwinkle Offline


Registered: 10/09/04
Posts: 7471
Loc: Cincinnati, OH, USA
Originally Posted By: mrdctaylor
Originally Posted By: Billbert
Nearly everything expands when heated, different materials expand at different rates and clearances change. Could have been a tolerance stack up problem.


Right. That's my thinking. But by the same token, a pressure test seems to be THE test for cooling systems. Maybe that's a misunderstanding on my part. Unfortunately, at least in some cases it gives a false reassurance that there is no issue. :-/
It is THE test-but many times it's better to test them hot. I had a Ford company van with the 4.6 ('12 E-250) that had this exact issue with both head gaskets-no leak cold, but there were telltale coolant tracks running into the block valley from both HGs. Ford dealer didn't feel like fixing it under warranty, they finally dumped in enough stop leak that the leaking stopped... mad
_________________________
06 Ram 3500 CTD 4X4(FG Venturi), 93 GMC C3500 6.2, 89 F-450 7.3, 98 XJ 4.0(XG8A), 05 xB(XG3600), 15 Transit 3.7, 03 Merc Grand Marquis 4.6 2V(XG2)

Top
#4692394 - 03/12/18 11:52 AM Re: Cooling system leak / pressure test question [Re: mrdctaylor]
Leo99 Offline


Registered: 03/30/14
Posts: 2872
Loc: NJ
I had the same symptoms on my Rav4. Losing coolant. Overflow tank emptying. It was the radiator cap.

Hope your leak is fixed. You're lucky to be vigilant and notice the leak before you lost your water pump and had to be towed or worse and overheated the engine and blew a head gasket.
_________________________
Without data you're just another person with an opinion. W. E. Deming

2003 Corolla 250,000 miles
2004 Rav4 333,000 miles
2015 Camry 40,000 miles

Top
#4692414 - 03/12/18 12:12 PM Re: Cooling system leak / pressure test question [Re: LeakySeals]
Trav Offline


Registered: 11/20/06
Posts: 18234
Loc: MA, Mittelfranken.de
Originally Posted By: LeakySeals
AKA Expansion tank.


?? The point was the metal expands not just the coolant.
_________________________
ASE L1, Master. Deutsch Meisterbrief.

Top
#4692449 - 03/12/18 01:00 PM Re: Cooling system leak / pressure test question [Re: Leo99]
mrdctaylor Offline


Registered: 06/05/03
Posts: 528
Loc: McGregor TX
Yeah, I'd already replaced the rad cap with an OEM one. I'd hoped that was it. He's driven it quite a bit since it was repaired and the level hasn't gone down any. I just hope this aftermarket water pump doesn't start [censored] out like that last one.
_________________________
12 Highlander 3.5L, 84K, M1 EP 0W20
02 Tacoma 3.4L, 211K, Napa Syn 5W30
17 Escape 2.0L, 28K, ???
02 Trailblazer 4.2L, 174K, Magnatec 5W30

Top