Larry365

Larry365

Active Member
1994 Discovery 300tdi (109,000 - 120,000 miles) Refurbed head by previous owner @ ~80,000 miles

A little trip to the dales last weekend (from Lincs) revealed a cooling issue. Thermo was stuck shut, so removed it to get home, topped up and then replaced once I got back. While driving home, my heaters were cold/hot/cold/hot so I assumed there must be an air lock. Temps held out so I got myself back.

I decided to go for a full flush, matrix, tank, block, rad, all pipes etc. Water only for now as I want to make sure I know how to bleed it before I start paying for coolant.

I have filled the system using various methods discussed on all the popular landy forums and nothing seems to be working. My preferred method, the one I last used and the one that makes the most sense to me is as follows.

1. All caps off, thermo, tank and rad.
2. Fill rad to top and replace cap
3. Fill tank to level and replace cap
4. Top up thermo and replace cap.
5. Run engine till warm and check tank level
6. Replace tank cap and check thermo level
Repeating steps 5 & 6 untill all air is out of system then for good measure, putting the vehicle at some good angles while engine running. Front up first, then side tilt with tank up.

I seem to hit a HUGE problem nearly every time, no matter which method I use. The thermo is above the header tank, if the engine is cold, ie thermo shut, then I can top up the block. As soon as the thermo opens, the whole lot drains into the tank and I am eventually left with a dry thermo housing. I am slightly confused as to how this is happening as I would assume that as long as the tank cap is on, the thermo should not drain. I am really confused.

If I open the tank while the thermo is still open, the thermo housing will drain into the tank.

How the hell do I keep water in the thermo housing. Its almost as if the tank is lower than it should be.

I am rapidly running out of hair to pull out and don't want to have to move on to my beard.

Its worth mentioning that I can see a slight "dampness" underneath the head gasket which would indicate to me that its time for a new one so I am now reluctant to run the engine for long periods of time but thinking about this issue in the most logical way, I cannot see how a failed gasket can cause this.

Any help would be HUGELY appreciated.

Merry Christmas
Harry


ps. Vehicle is in a garage with a little heater under the engine in case we get a freeze on the next few days.
 
Larry365 said:
1994 Discovery 300tdi (109,000 - 120,000 miles) Refurbed head by previous owner @ ~80,000 miles

.......................................................I seem to hit a HUGE problem nearly every time, no matter which method I use. The thermo is above the header tank, if the engine is cold, ie thermo shut, then I can top up the block. As soon as the thermo opens, the whole lot drains into the tank and I am eventually left with a dry thermo housing. I am slightly confused as to how this is happening as I would assume that as long as the tank cap is on, the thermo should not drain. I am really confused.

If I open the tank while the thermo is still open, the thermo housing will drain into the tank.

How the hell do I keep water in the thermo housing. Its almost as if the tank is lower than it should be.

I am rapidly running out of hair to pull out and don't want to have to move on to my beard.

Its worth mentioning that I can see a slight "dampness" underneath the head gasket which would indicate to me that its time for a new one so I am now reluctant to run the engine for long periods of time but thinking about this issue in the most logical way, I cannot see how a failed gasket can cause this.

Any help would be HUGELY appreciated.

Merry Christmas
Harry


ps. Vehicle is in a garage with a little heater under the engine in case we get a freeze on the next few days.
Click to expand...

If your main issue is that the coolant in the 'stat housing drain into the header tank if both caps are off, then I would say this is perfectly normal behaviour.

If you leave the header tank cap on, then top up the stat housing, then cap it, you can now check the level in the header tank with draining the stat housing.

You can't have both open at the same time, is the point.

Dave

PS. After you've topped-up and capped off the rad and stat housing, leave the vehicle ticking over with the header tank cap off for a few minutes.

If you've still got plain water in the cooling circuit I would be getting that out today - not so much from the viewpoint of anti-freeze but a lack of rust inhibitors will cause you trouble.

Bleeding a TDi 300 is not a big deal at all, so unless you are going to do the head very soon, get some proper coolant in her.
 
thebiglad said:
If you leave the header tank cap on, then top up the stat housing, then cap it, you can now check the level in the header tank with draining the stat housing.

You can't have both open at the same time, is the point.
Click to expand...

Unfortunately this is exactly what I have been doing. Its fine as long as I stay still however as soon as I got for a drive all the water ends up in the header tank. Tank fills to the top, stat housing dry, coolers cold, stat has no water around it. I just don't get it. The only way I think this could be happening is if my tank has a hole or faulty cap. I cant hear anything when its hot though so i'm in no rush to go buy a new one.

Appreciate what you are saying about getting some coolant in, I'm on it!
 
Larry365 said:
Unfortunately this is exactly what I have been doing. Its fine as long as I stay still however as soon as I got for a drive all the water ends up in the header tank. Tank fills to the top, stat housing dry, coolers cold, stat has no water around it. I just don't get it. The only way I think this could be happening is if my tank has a hole or faulty cap. I cant hear anything when its hot though so i'm in no rush to go buy a new one.

Appreciate what you are saying about getting some coolant in, I'm on it!
Click to expand...

Hi Harry, my only other suggestion is that you have a faulty valve in the 'Y'-shaped pipe that goes between the 'stat housing, the header tank and the top of the rad.

Although for the cost of one I'd be inclined to get a new header tank cap as well.

Sorry I can't be more definitive, Merry Christmas to all our readers,

Dave
 
thebiglad said:
Hi Harry, my only other suggestion is that you have a faulty valve in the 'Y'-shaped pipe that goes between the 'stat housing, the header tank and the top of the rad.

Although for the cost of one I'd be inclined to get a new header tank cap as well.

Sorry I can't be more definitive, Merry Christmas to all our readers,

Dave
Click to expand...

Would that be the little round chap? Better nip to rimmer bros before it closes. The advantages of living 2 miles away. Might just get a whole tank while i'm there. I like the look of those clear aftermarket ones, hopefully they stock em.

Merry Christmas
 
Larry365 said:
Would that be the little round chap? Better nip to rimmer bros before it closes. The advantages of living 2 miles away. Might just get a whole tank while i'm there. I like the look of those clear aftermarket ones, hopefully they stock em.

Merry Christmas
Click to expand...

Yes that's the one, approx 1 inch in diam with two pipes going in and one going out.

If you can buy just the valve on it's own can you send me details, I'd like to get a couple in stock.
 
thebiglad said:
Yes that's the one, approx 1 inch in diam with two pipes going in and one going out.

If you can buy just the valve on it's own can you send me details, I'd like to get a couple in stock.
Click to expand...

Rimmers only sell the valve with the pipes at £13. I've asked them to contact supplier and see if they can stock them separately as there is a big demand for just the valve etc bs etc. They're gonna get in touch and I'll let you know.

Got myself a new cap but held off paying 13 quid. If I can't source a valve on its own on the next couple of days ill have to suck it up and fork out.
 
Topped up stat again and 5 miles later, all seems ok but I darent open the header tank to check level as it'll just drain all the water out the stat housing. What exactly does this valve do. Does it allow flow from stat to tank or is it one way from tank to stat?
 
i filled the tank then once it wouldnt take anymore i opened the bleeds and topped them up
 
On this forum its been said the valve can bs replaced with a tee piece and lr did that on later models anyway, the valve on mine was blocked and in the process of unblocking it ...it became a tee piece :)

I dont know why yr expansion is filling but the heater matrix might need filling by disconnecting a hose, then it should work.

It is a bit odd one has to top up via the thermo every time after removing the exp cap...but that does seem to be the case......odd if so...but not a major as one should not lose fluid and need to check it often...maybe the clear tanks solve that inconvenience?
 
Last edited:
Yeh I am definitely ordering a clear tank as soon as possible. I'll look in to replacing that valve with a T. It strange, if I top up from the thermo with the header at the correct level, it will slowly drain away. Where? I don't know; but definitely not into the header tank. New cap and no leaks, physics simply wont allow it.

I am starting to think the head gasket has failed more than external evidence would suggest and wondering whether the water is finding its way out of the stat housing and into the engine.

I think I am going to leave this issue to one side until I have had the head off and drained the sump.

Tasks for the next couple of weeks.

Head off, checked, gasket replaced and all else that goes with it.
New header tank, replace valve with either T or new valve.
Replace breather cyclone and clean all air intake related stuff.
I'm sure there is a load more I had in mind but I get a bit slow this time of night.

Wish me luck as I've never attempted a head before but there seems to be plenty of guides and helpful advice so figure I can't go wrong if I take my time. Besides, if I get stuck, I can always come pest you guys :D
 
KiwiTDI said:
It is a bit odd one has to top up via the thermo every time after removing the exp cap...but that does seem to be the case......odd if so...but not a major as one should not lose fluid and need to check it often...maybe the clear tanks solve that inconvenience?
Click to expand...


That is definitely NOT the case on a TDi 300 where the cooling system is working properly.

Dave
 
dogsbody said:
PRAT
and I'll say the same in the other two threads where you've stuck your problem.
Click to expand...

I dont follow. I thought the thread would be more suited in the engines thread as the other two threads are not labled appropriately. Posted a link in this thread and the other so that people who have been helping me so far can see where I am at. Unless ive misunderstood what you are implying here.
 
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