Tracking My Car Coolant Being Forced out of Reservoir

terrydtdi

Veteran Member
Joined
May 16, 2006
Location
Charleston S.C.
TDI
2000 MK4 TDI Jetta 5spd
Trying to figure why my coolant is being forced out of the reservoir.

It’s only happening under wide open throttle. I have ARP head studs so I wouldn’t think I would be lifting the head. I have the very knowledgeable Euro car friend who believes it could be a radiator issue not being able to flow enough coolant. It’s the original radiator. See my mods below. Any other ideas?

Thanks
 

Mongler98

Top Post Dawg
Joined
Mar 23, 2011
Location
Northern MD (HAGERBUSH)
TDI
98 Jetta TDI AHU 1.9L (944 TDI swap in progress)
probably head gasket (sort of) but there are OTHER things that CAN cause this

EGR leak
low coolant high temps
poorly clogged system
bad thermostat

however, its probably the head lift
I am running a nasty turbo at 28PSI (was 32) and i also have ARP studs and i still have lift. Problem is that once it starts, chances are you have a out of true head and or block.

the ONLY way to fix this, is to back off the boost and fuel if it really is head lift.
Pull the head, measure the block from the TOP of the crank journals to the top of the block and to measure head run out.
I hate to tell you this but if its bad, this is the only way to find out how bad it is. ive been diving down this hole for years now, im just glad its parked due to a runaway and its for a swap (some day)

There is ONE thing you can check, your ARP torque
there IS a re torquing procedure for this, its 5 heat cycles twice to re torque if necessary and hope you put that lube that came with the pack on all surfaces, not so much the threads, the washer and the head and the nut. that is CRITICAL to getting a true torque, not just putting it on the threads.
 

terrydtdi

Veteran Member
Joined
May 16, 2006
Location
Charleston S.C.
TDI
2000 MK4 TDI Jetta 5spd
I’m getting a warm hose from the thermostat, and a very hot hose on the upper drivers side. The upper drivers side feels like it doesn’t have any Liquide in it. Does it sound like a bad thermostat? There isn’t hardly any coolant flowing into the reservoir like it normally is. Sounds kind of like the thermostat is stuck closed.
 

terrydtdi

Veteran Member
Joined
May 16, 2006
Location
Charleston S.C.
TDI
2000 MK4 TDI Jetta 5spd
probably head gasket (sort of) but there are OTHER things that CAN cause this

EGR leak
low coolant high temps
poorly clogged system
bad thermostat

however, its probably the head lift
I am running a nasty turbo at 28PSI (was 32) and i also have ARP studs and i still have lift. Problem is that once it starts, chances are you have a out of true head and or block.

the ONLY way to fix this, is to back off the boost and fuel if it really is head lift.
Pull the head, measure the block from the TOP of the crank journals to the top of the block and to measure head run out.
I hate to tell you this but if its bad, this is the only way to find out how bad it is. ive been diving down this hole for years now, im just glad its parked due to a runaway and its for a swap (some day)




There is ONE thing you can check, your ARP torque
there IS a re torquing procedure for this, its 5 heat cycles twice to re torque if necessary and hope you put that lube that came with the pack on all surfaces, not so much the threads, the washer and the head and the nut. that is CRITICAL to getting a true torque, not just putting it on the threads.
I installed the ARP headstuds as directed. I’m going to be due for a TB in About 8,000 miles. That may come sooner then later now.

It definitely appears to be a blockage one side has coolant in the hose, and driver side doesn't have any coolant.
 
Last edited:

Macradiators.com

Veteran Member
Joined
Nov 2, 2015
Location
Romania
TDI
2.0 CR 360hp
I have ARP and still have pressure in my water system.
Putting new head gasket next week and remount everything after the head is tested and surfaced.
I run 2.9 bar boost.
 

Mongler98

Top Post Dawg
Joined
Mar 23, 2011
Location
Northern MD (HAGERBUSH)
TDI
98 Jetta TDI AHU 1.9L (944 TDI swap in progress)
cant hurt to flush the crap out of it with detergent and water, new thermostat and possible water pump, you will know when you take it off.
hope its not head lift
 

terrydtdi

Veteran Member
Joined
May 16, 2006
Location
Charleston S.C.
TDI
2000 MK4 TDI Jetta 5spd
I have ARP and still have pressure in my water system.
Putting new head gasket next week and remount everything after the head is tested and surfaced.
I run 2.9 bar boost.

Yeah I think that's what's going on here. I think my water pump impeller may be spinning on the shaft.
 

terrydtdi

Veteran Member
Joined
May 16, 2006
Location
Charleston S.C.
TDI
2000 MK4 TDI Jetta 5spd
cant hurt to flush the crap out of it with detergent and water, new thermostat and possible water pump, you will know when you take it off.

hope its not head lift
I think I have a bad water pump, which cause the blown head gasket allowing combustion pressure into the cooling ducts, the hoses feel like they are about to burst. I had to park the car till next week. I'll be pulling it apart.

You would think of the head was lifting there would be signs around the head not just a coolant problem.
Lots of times the head lifting will only show signs of evidence of exhaust in the coolant reservoir .
 

Mongler98

Top Post Dawg
Joined
Mar 23, 2011
Location
Northern MD (HAGERBUSH)
TDI
98 Jetta TDI AHU 1.9L (944 TDI swap in progress)
if you have overheated the darn thing with a bad pump, well your head and possibly the block are not true anymore.
dude, ive been down this road, i hate this road, it sucks
 

adamss24

Veteran Member
Joined
Nov 2, 2005
Location
Great Britain
TDI
audi a4 2.5 tdi 98 quatrro 6speed
I have rebuilt a vw golf AHF 1.9 tdi engine the summer before the last, it had a strange overheating issue that the temp will climb only at idle- full throttle would have kept the darn thing reasonably cool ! I took the head off and found all coolant passages eroded close to the piston/compression passages and replaced-it with a good head only to have the same issue again ! After a new radiator, new heater matrix (it wouldn't give heat in the cabin neither) i took the pump off (owner changed the timing belt and water pump a year before !) to be greeted by a completely eroded steel impeller hence the lack of cooling ! It was a Hepu water pump, trully rubbish and expensive too ! I suggest you pull the thermostat off and feel with your fingers if the pump impeller is spinning on the shaft !
Guess what, last week i've done a timing belt on a 1.6 petrol Ibiza which had also overheating issue, same hepu pump with all impeller blades broken ! The pump/timing belt was done end of 2017 ! I've fitted a Airtex plastic impeller pump and no issues since...was afraid head gasket was blown though !
 

atomicalexc

Member
Joined
Mar 29, 2019
Location
San Diego
TDI
2014 Golf
Just too much coolant? If you're not losing it and it's not being fouled, it probably is just being pushed out when it's hot. This shouldn't be the case when you filled it up properly, but maybe you got a bad batch of coolant with a different thermal expansion coefficient. Best of luck.
 

terrydtdi

Veteran Member
Joined
May 16, 2006
Location
Charleston S.C.
TDI
2000 MK4 TDI Jetta 5spd
I have rebuilt a vw golf AHF 1.9 tdi engine the summer before the last, it had a strange overheating issue that the temp will climb only at idle- full throttle would have kept the darn thing reasonably cool ! I took the head off and found all coolant passages eroded close to the piston/compression passages and replaced-it with a good head only to have the same issue again ! After a new radiator, new heater matrix (it wouldn't give heat in the cabin neither) i took the pump off (owner changed the timing belt and water pump a year before !) to be greeted by a completely eroded steel impeller hence the lack of cooling ! It was a Hepu water pump, trully rubbish and expensive too ! I suggest you pull the thermostat off and feel with your fingers if the pump impeller is spinning on the shaft !
Guess what, last week i've done a timing belt on a 1.6 petrol Ibiza which had also overheating issue, same hepu pump with all impeller blades broken ! The pump/timing belt was done end of 2017 ! I've fitted a Airtex plastic impeller pump and no issues since...was afraid head gasket was blown though !

Hmm I’ve always thought the Hepu was one of the better pumps. I’ll be pulling it out soon, and I’ll report back. I pulled the t-stat out and tried to feel the impeller, not sure if I couldn’t feel up there enough but wasn’t able to tell much there. It’s definitely not moving coolant. Just a very slight trickle coming into the return line. The radiator is original to the car so I’ll be replacing that. Thanks
 

SilverGhost

Veteran Member
Joined
Mar 25, 2005
Location
Back in So Flo - St Lucie
TDI
'05 Golf - totaled :(, wife's '13 Beetle - buy back, TDIless
I have had weird overheating issues trace back to water pump. A couple of the pumps with plastic impeller you could reach in the t-stat hole and it would feel tight, but after we pulled them apart we found cracks. Once the coolant heated up and impeller got warm it started slipping.

We have seen some weird long term issues with metal impellers, including a bad bearing - impeller wobbled and chewed up the block. That one needed an engine. Also the steel impellers have rusting issues, where as I have seen at least one brass impeller that should be much better.

One Golf with 2slow ended up having a plugged radiator and cracked impeller causing overheating issues. So, could be more than one thing causing your woes.

Jason
 

terrydtdi

Veteran Member
Joined
May 16, 2006
Location
Charleston S.C.
TDI
2000 MK4 TDI Jetta 5spd
Just wanted to get back with everybody on this post. I had a spare head and I did a more aggressive port job on, the machine shop did a valve job on it, and added Whitbread's double valve springs, along with a Colt stage 2 cam. I ended up swapping out the radiator. Installed new TB. I believe the problem was a head gasket.
The car is running better then it ever has.
 

Poor King

Well-known member
Joined
May 20, 2020
Location
NY
TDI
92 Jetta, 03 Jetta
I love it when a problem is solved and the OP returns to inform the exact nature of the cause. With most threads, you are left hanging with questions but this thread will be very valuable for myself in the near future.

Was it just a defective headgasket, improper install, or wrong thickness?
 
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