Recent Topics
$14 5qt. QS 10w-40 syn blend + $5 GC - wallys
by lairdwd
Yesterday at 09:06 PM
Synthetic from dino?
by S2K
Yesterday at 08:35 PM
Voltage fluctuation 2012 Elantra
by schuylkill
Yesterday at 08:28 PM
Tranfer Case 2016 GMC Sierra 1500 6.2 8 speed
by dareo
Yesterday at 07:39 PM
Caliper slide pin questions
by ZZman
Yesterday at 07:24 PM
Perfect Afternoon with F7Fs
by Yah-Tah-Hey
Yesterday at 06:10 PM
Blending E85 to use as cleaner in non-FFV
by ltslimjim
Yesterday at 05:33 PM
01 Tahoe instrument cluster replacement question
by mjk
Yesterday at 05:25 PM
Reasonable price to pay some one to detail?
by Colt45ws
Yesterday at 05:09 PM
FCA upheaval--Marchionne ill, Jeep CEO takes over
by Carmudgeon
Yesterday at 04:42 PM
Duck Boat
by Zee09
Yesterday at 04:23 PM
What are these valves and can I use them to...
by E150GT
Yesterday at 04:06 PM
OBD Tool
by dawgn86
Yesterday at 03:31 PM
Any experience with the new FA-4 oils?
by SubaJew
Yesterday at 03:24 PM
What's the average life (in miles) of mc tires
by JeepWJ19
Yesterday at 03:00 PM
Car Recommendation: haul an electric scooter
by brueggma1
Yesterday at 02:54 PM
300ZX Starter replacement
by aquariuscsm
Yesterday at 02:50 PM
Finally Let the HF/Greyhound Franken Mower Go
by javacontour
Yesterday at 02:17 PM
You know its hot when...
by Chris142
Yesterday at 02:09 PM
2015 Mazda 3 - Exhaust CAM Actuator Seal - HM Oil?
by buster
Yesterday at 01:16 PM
Newest Members
ppreedom, krugger, jznwhite, S2K, tweak999
65524 Registered Users
Who's Online
47 registered (barkingspider, Brad_C, ammolab, 77GrandPrix, BHopkins, bbhero, 5 invisible), 1076 Guests and 29 Spiders online.
Key: Admin, Global Mod, Mod
Forum Stats
65524 Members
67 Forums
287437 Topics
4795211 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: 596
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!
_________________________
02 Tacoma 3.4L, 215K, Magnatec 10W30
02 Trailblazer 4.2L, 179K, Edge HM 10W40
12 Highlander 3.5L, 88K, M1 EP 0W20
17 Escape 2.0L, 31K, Hav ProDS 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: 368
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: 596
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. :-/
_________________________
02 Tacoma 3.4L, 215K, Magnatec 10W30
02 Trailblazer 4.2L, 179K, Edge HM 10W40
12 Highlander 3.5L, 88K, M1 EP 0W20
17 Escape 2.0L, 31K, Hav ProDS 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: 19346
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: 6625
Loc: Hudson, NH
AKA Expansion tank.
_________________________
06 Escalade 6.0L AWD 160k. M1 5w30 Fram TG
03 Maxima 3.5L 152k ST HM 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: 7743
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: 3117
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 359,000 miles
2015 Camry 59,000 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: 19346
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: 596
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.
_________________________
02 Tacoma 3.4L, 215K, Magnatec 10W30
02 Trailblazer 4.2L, 179K, Edge HM 10W40
12 Highlander 3.5L, 88K, M1 EP 0W20
17 Escape 2.0L, 31K, Hav ProDS 5W30

Top