Hellish coolant leak

Chris_TDI_98

Veteran Member
Joined
Jul 19, 2012
Location
Hartford, CT
TDI
1998 Jetta TDI 1.9L mk3 1Z AHU
After a month of below freezing over night weather, my 98 tdi’s coolant leak has gone from dripping out roughly a few ounces (75 mL) per day, to now it will lose a gallon (3.7 L) of coolant gushing out in 15 seconds, almost as fast as I can pour it into the spherical overflow reservoir.

I replaced the coolant flange located on the head, front and center when you open the hood and look at the engine, but that wasn’t the source of the leak.

Any suggestion on locating the source of the coolant leak.

Is there a diagram of just the coolant system ?!

The car had no Air Conditioning, it’s a base model TDI, no options (except central locking).





 
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Mongler98

Top Post Dawg
Joined
Mar 23, 2011
Location
COLORADO (SE of Denver)
TDI
98 Jetta TDI AHU 1.9L (944 TDI swap in progress) I moved so now i got nothing but an AHU in a garage on a pallet.
toss that POS part in the trash and go get a CNC made all aluminum replacement, i have no idea if anyone makes it still, i got mine from a user here, again, it was years ago and i forgot, but the new part is SOLID.
 

ToddA1

Top Post Dawg
Joined
Aug 3, 2011
Location
NJ 08002
TDI
'96 B4V, '97 B4 (sold), '97 Jetta (scrapped)
You’re losing a gallon/15 seconds, and you can’t find the leak?

-Todd
 

oilhammer

Certified Volkswagen Nut & Vendor
Joined
Dec 11, 2001
Location
outside St Louis, MO
TDI
There are just too many to list....
This thread is comical. LMAO.... :D:):D:p

Posts #2, 5, and 6 tie for the win.

I'll throw my jab in: Now you found you BEST theft prevention: vital fluids leaving puddles under the car! BRILLIANT!!!
 

Steve Addy

Top Post Dawg
Joined
Aug 7, 2002
Location
Iowa
TDI
97 Mk3
Is the sphere connected directly to the hoses under the injection pump such that the coolant would leak out so quickly ??
The weeping from the IP will destroy hoses and there are two right under the IP distributor head. If you did not fix the IP distributor leak it's likely that the hoses under there are ruined...and leaking.

It wouldn't be the first time this has happened.

At any rate, it doesn't matter where the reservoir is in the system if there's a leak, it will run out just as fast as you add it.

If you can't visually see it from standing over the engine then you'll have to get it up off the ground. If your car is lowered that can be a difficult task.

Steve
 

Jetta SS

Veteran Member
Joined
Oct 30, 2006
Location
Grand Bay, AL
TDI
'98 Jetta
20 years is a long time on hoses. Might as well change em all while you got the coolant drained and the weather is good. :)
 

Chris_TDI_98

Veteran Member
Joined
Jul 19, 2012
Location
Hartford, CT
TDI
1998 Jetta TDI 1.9L mk3 1Z AHU
hoses. Might as well change em all while you got the coolant drained
+1. Is there even a list here on TDIclub of all the coolant hoses (with name, VW part number, and universal interchange part number) for base model jetta TDI A3/mk3 1z AHU Engine with no AirCon ?!
 

Jetta SS

Veteran Member
Joined
Oct 30, 2006
Location
Grand Bay, AL
TDI
'98 Jetta
+1. Is there even a list here on TDIclub of all the coolant hoses (with name, VW part number, and universal interchange part number) for base model jetta TDI A3/mk3 1z AHU Engine with no AirCon ?!

I couldn't find one. I did mine last year, and looked around prior for info.
 

Chris_TDI_98

Veteran Member
Joined
Jul 19, 2012
Location
Hartford, CT
TDI
1998 Jetta TDI 1.9L mk3 1Z AHU
I couldn't find one. I did mine last year, and looked around prior for info.
If you wouldn’t mind could you maybe look at your online purchase history or look around on the computer and see if you saved a list of the hoses because that’d save a lot of duplicated time and effort.
 

tdidieselbobny

Top Post Dawg
Joined
Apr 4, 2005
Location
Stafford,NY (WNY)
TDI
'03 Galactic Blue Jetta TDI, '15 Silk Blue Golf Sportwagen TDI
Parts Place for VW's has a hose "kit" listed for the 98 TDI for $159.95. Doesn't list what hoses are in it, their web address is www.partsplaceinc.com , not sure if it's listed on there, I'm looking at the catalog I got in mail.
 

JETaah

Vendor , w/Business number
Joined
Jan 18, 2001
Location
mi 48836
TDI
96 B4V, 1999.5 jettaIV,2005 BEW Beetle
Beware of no name or unfamiliar brand aftermarket hoses. They are liable to not last as long as your 20 year old ones. These days it is hard to find reputable brands for these old cars (Gates, etc...)
The coolant hoses on my 96 Passat are all original with exception of the cluster under the IP for obvious reasons.
Maybe I am an optimist but when checking them out closely I can't find a reason to replace them. Same for just about every VW I've owned since 1978.
Let us know how it goes with PartsPlace.
 
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Jetta SS

Veteran Member
Joined
Oct 30, 2006
Location
Grand Bay, AL
TDI
'98 Jetta
Beware of no name or unfamiliar brand aftermarket hoses. They are liable to not last as long as your 20 year old ones. These days it is hard to find reputable brands for these old cars (Gates, etc...)
The coolant hoses on my 96 Passat are all original with exception of the cluster under the IP for obvious reasons.
Maybe I am an optimist but when checking them out closely I can't find a reason to replace them. Same for just about every VW I've owned since 1978.
Let us know how it goes with PartsPlace.
I've been on the side of the road before in the summer on a 110 deg day in AZ with a blown hose before (an upper rad hose that was only 6 yrs old). I think climate has a lot to do with it. I've never looked to see what the manufacturers recommend for replacement life. Maybe it's just up to inspection, your 22 years is outstanding.
 
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Jetta SS

Veteran Member
Joined
Oct 30, 2006
Location
Grand Bay, AL
TDI
'98 Jetta
If you wouldn’t mind could you maybe look at your online purchase history or look around on the computer and see if you saved a list of the hoses because that’d save a lot of duplicated time and effort.

I had to source the upper hose off ebay due to everyone else wanting big bucks. - I have A/C and this ends up being a special hose. For everything else I just sent an email to metalman parts saying I needed all hoses except the one. That way I didn't have to waste my time looking all that up.
 

Chris_TDI_98

Veteran Member
Joined
Jul 19, 2012
Location
Hartford, CT
TDI
1998 Jetta TDI 1.9L mk3 1Z AHU
The leak was NOT coming out of the original coolant flange, because with the new flange installed, the leak still happens. This is a huge challenge to diagnose where the leak is coming from, because it leaks out so fast. Can anyone point me to a diagram of the coolant system hoses. There appears to be a metal tube which some of the smaller hoses attach onto. Is this how coolant gets into the head and into the block?
 

JETaah

Vendor , w/Business number
Joined
Jan 18, 2001
Location
mi 48836
TDI
96 B4V, 1999.5 jettaIV,2005 BEW Beetle
How about this...
Take the small overflow hose off the reservoir and plug the reservoir's nipple.
Get a bicycle pump and adapt it to the hose and start pumping. It is bound to show up if it is externally leaking.
 

Steve Addy

Top Post Dawg
Joined
Aug 7, 2002
Location
Iowa
TDI
97 Mk3
The cooling system on these is really easy to figure out, just trace the hoses you can see. The coolant pipe is easy to find, it runs from one of the heater core lines around the front of the engine and down to a hose going to the WP.

There's nothing hidden with this system, it's all right there in front of you. You need to get the car off the ground and watch underneath when you're adding coolant / water to the system. With this much coming out so quickly I don't understand why you can't locate the problem, there will be moisture all around the leak.

Steve
 

RoseBud68

Veteran Member
Joined
Dec 16, 2016
Location
PSL FL
TDI
'99 mk3 Jetta 1.9
The cooling system on these is really easy to figure out, it's all right there in front of you.. I don't understand why you can't locate the problem, there will be moisture all around the leak.

Steve
You would think it would be that easy.....:D
 

TDIDaveNH

Left Lane Coal Roller at Large
Joined
Feb 17, 2009
Location
North Conway, NH
TDI
1997 Passat TDI x2 1984 Buick Century 4.3 diesel
My bet is it's the metal clip that's not seated on the lower hose at the radiator. This happened to me once but I wasn't loosing it quite as fast as the OP here is.

I mean stick a hose in it, and find where it's gushing out, wherever that may be. It might not be a hose or sensor or flange.
Where is the like button that you can press an unlimited number of times?
 
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Steve Addy

Top Post Dawg
Joined
Aug 7, 2002
Location
Iowa
TDI
97 Mk3
My bet is it's the metal clip that's not seated on the lower hose at the radiator. This happened to me once but I wasn't loosing it quite as fast as the OP here is.



Where is the like button that you can press an unlimited number on times?
Ditto, that's about the best suggestion that's come up TBH.

I can think of several faults that can cause gushing coolant. Lower rad hose clips at either end, lower rad hose o-rings split at either end. WP cracked thermostat housing or failed WP housing to block o-ring. Lower rad hose chafing on front engine mount bracket etc.

There's also the possible frost plug failure too. That's especially if it's not had good factory spec coolant in it for life.

At some point you have to find it, I mean really, gushing coolant and you can't find it?

Steve
 
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