855 tdi cooling system pressurising.

Ninjabob81 · May 31st, 2019, 16:14

Hi all, as title really, constantly losing coolant, have replaced the expansion tank cap, no misfires, no coolant in the oil or vice versa, no drop in performance, temp gauge never rises above half, and yet after a decent run I can pull to a stop and get the tell tale wisp of steam out of the bonnet shutline, open it up and hey presto no coolant. I’ve pressure tested the cooling system with a sealey kit and it held 16psi all day long, admittedly this was done on a cold engine as I was short on time. There’s no evidence of coolant staining on the exhaust tip, coolant never smells of exhaust fumes, no cold hoses, coolant is definitely circulating. Header tank looks original so I’m tempted to bing a new one on just in case it has a split somewhere. Genuinely a little confused, and just wondered if anyone’s suffered the same fate with the tdi engine? Are headgaskets common on these? Does it sound like headgasket to you?

Suggestions please!
Thanks, Rob.

rudi dudi · May 31st, 2019, 16:21

These dont suffer with any sort of problems... So a head gasket whilst not being completely out question is not a common component that fails.
I would try a new expansion tank and cap as a first port of call if I was experiencing your problems.

rudi dudi · May 31st, 2019, 17:03

Just been thinking and whilst not specific to the tdi engine... These mk1 70's do a habit of leaking coolant from the heater matrix.
Now you would expect the pressure test you performed to highlight this but might be worth a look.
Passenger side footwell pull the centre console carpet back a bit and have a look at the matrix for any signs of potential leaks.

huron · May 31st, 2019, 17:04

Have you just changed the coolant? If so it takes ages to get all the air out which could be why your tank level drops. Can you see any sign of water on the ground?

V70Zig · May 31st, 2019, 17:06

Quote:

Originally Posted by rudi dudi

These dont suffer with any sort of problems... So a head gasket whilst not being completely out question is not a common component that fails.
I would try a new expansion tank and cap as a first port of call if I was experiencing your problems.

Pop the bonnet and manually give it some revs......might show up....or not. Worked on my old V70. Pipe had a split underneath the oil filter.......Not visible till I revved it. No water on the ground as it ****ed out onto the exhaust and evaporated immediately..................................

Martin Cox · May 31st, 2019, 17:18

I'd agree with Rudi Dudi.

The expansion tank caps are known to fail with age. PFS Volvo will sell you an aftermarket cap for £7 or so or the genuine article for £20. I've no experience of the aftermarket cap but I suspect it probably comes from the same factory.

I'm assuming that to use the Sealey kit, you remove the expansion tank cap and replace it with one that allows you to connect the kit and pressurise the system. The fact that the system then held pressure all day adds weight to the likelihood of it being the cap at fault.

I'd start by just replacing the cap.

Thinking further, it might be worth repeating the pressure test when the engine is hot. Also the fact that you're seeing some steam along the bonnet shut line suggest's its more likely to be something under the bonnet than the heater matrix. Is the steam more pronounced on one side or the other?

Martin

1998 V70 Tdi auto 224,000 miles

Ninjabob81 · May 31st, 2019, 20:35

Cheers for all the replies so far, forgot to say in the original post I have had the carpets back in the near side and it’s all bone dry with no signs of the matrix leaking. I have already replaced the cap albeit with a non genuine one. The steam I mentioned is what I can only assume is being vented off by the cap. Just ordered a new expansion tank from eurocrap parts which will arrive on Monday.

As for holding some revs on it when it’s hot I’m gonna have to find somewhere quiet to do it (decatted, straight through system with a small resonator at the back &#128514

as I don’t want to get the neighbours upset... might be a job for the weekend.

I’ll see if I can borrow the pressure tester again and do it again hot.

Again, thanks for all the suggestions, and keep them coming!! Determined to get to the bottom of it.

Rob.

V70Zig · Jun 1st, 2019, 06:04

Have a look at this post - https://www.volvoforums.org.uk/showthread.php?t=267889
Mine did not show at idle, only when revved......damn small pinhole it was.
If you pressure tested on a cold engine then the pipes will be harder and a small pinhole might not open up ?
Try again with a hot engine (careful when you take the cap off) or rev it up out in the sticks somewhere. Good luck,

May 31st, 2019, 17:04	#4
huron Master Member Last Online: Dec 19th, 2020 16:24 Join Date: Apr 2009 Location: Bodmin	Have you just changed the coolant? If so it takes ages to get all the air out which could be why your tank level drops. Can you see any sign of water on the ground? __________________ huron 2009 V70 2.4 geartronic in red.

May 31st, 2019, 17:18	#6
Martin Cox VOC Member Last Online: Yesterday 09:24 Join Date: Dec 2001 Location: Hull	I'd agree with Rudi Dudi. The expansion tank caps are known to fail with age. PFS Volvo will sell you an aftermarket cap for £7 or so or the genuine article for £20. I've no experience of the aftermarket cap but I suspect it probably comes from the same factory. I'm assuming that to use the Sealey kit, you remove the expansion tank cap and replace it with one that allows you to connect the kit and pressurise the system. The fact that the system then held pressure all day adds weight to the likelihood of it being the cap at fault. I'd start by just replacing the cap. Thinking further, it might be worth repeating the pressure test when the engine is hot. Also the fact that you're seeing some steam along the bonnet shut line suggest's its more likely to be something under the bonnet than the heater matrix. Is the steam more pronounced on one side or the other? Martin 1998 V70 Tdi auto 224,000 miles Last edited by Martin Cox; May 31st, 2019 at 17:26. Reason: Additional content

Jun 1st, 2019, 06:04	#8
V70Zig Master Member Last Online: Apr 10th, 2024 16:20 Join Date: Sep 2012 Location: Loughborough	Have a look at this post - https://www.volvoforums.org.uk/showthread.php?t=267889 Mine did not show at idle, only when revved......damn small pinhole it was. If you pressure tested on a cold engine then the pipes will be harder and a small pinhole might not open up ? Try again with a hot engine (careful when you take the cap off) or rev it up out in the sticks somewhere. Good luck, __________________ 2008 V70 SE D5 Auto 185 ...now 205 Volvo Polestar......190k Passed away - 1999 V70 2.5tdi Auto 340632 miles, RIP.

May 31st, 2019, 16:14	#1
Ninjabob81 Senior Member Last Online: Apr 21st, 2024 22:46 Join Date: Mar 2016 Location: Derbyshire	855 tdi cooling system pressurising. Hi all, as title really, constantly losing coolant, have replaced the expansion tank cap, no misfires, no coolant in the oil or vice versa, no drop in performance, temp gauge never rises above half, and yet after a decent run I can pull to a stop and get the tell tale wisp of steam out of the bonnet shutline, open it up and hey presto no coolant. I’ve pressure tested the cooling system with a sealey kit and it held 16psi all day long, admittedly this was done on a cold engine as I was short on time. There’s no evidence of coolant staining on the exhaust tip, coolant never smells of exhaust fumes, no cold hoses, coolant is definitely circulating. Header tank looks original so I’m tempted to bing a new one on just in case it has a split somewhere. Genuinely a little confused, and just wondered if anyone’s suffered the same fate with the tdi engine? Are headgaskets common on these? Does it sound like headgasket to you? Suggestions please! Thanks, Rob.

May 31st, 2019, 16:21	#2
rudi dudi DPF free.FCUK Greta he he Last Online: Mar 28th, 2024 13:38 Join Date: Jun 2012 Location: Bristol	These dont suffer with any sort of problems... So a head gasket whilst not being completely out question is not a common component that fails. I would try a new expansion tank and cap as a first port of call if I was experiencing your problems.

May 31st, 2019, 17:03	#3
rudi dudi DPF free.FCUK Greta he he Last Online: Mar 28th, 2024 13:38 Join Date: Jun 2012 Location: Bristol	Just been thinking and whilst not specific to the tdi engine... These mk1 70's do a habit of leaking coolant from the heater matrix. Now you would expect the pressure test you performed to highlight this but might be worth a look. Passenger side footwell pull the centre console carpet back a bit and have a look at the matrix for any signs of potential leaks.

May 31st, 2019, 20:35	#7
Ninjabob81 Senior Member Last Online: Apr 21st, 2024 22:46 Join Date: Mar 2016 Location: Derbyshire	Cheers for all the replies so far, forgot to say in the original post I have had the carpets back in the near side and it’s all bone dry with no signs of the matrix leaking. I have already replaced the cap albeit with a non genuine one. The steam I mentioned is what I can only assume is being vented off by the cap. Just ordered a new expansion tank from eurocrap parts which will arrive on Monday. As for holding some revs on it when it’s hot I’m gonna have to find somewhere quiet to do it (decatted, straight through system with a small resonator at the back &#128514 as I don’t want to get the neighbours upset... might be a job for the weekend. I’ll see if I can borrow the pressure tester again and do it again hot. Again, thanks for all the suggestions, and keep them coming!! Determined to get to the bottom of it. Rob.

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