Td5 D2 engine - coolant leak ..EEK!!

Noticed a wet patch on the driveway yesterday just when I was going out. It was obvious that it was engine coolant from the look and feel of the residue. 

Looking under the bonnet, the coolant reservoir level had dropped and the pipework connecting the exhaust cooler on the front of the engine was wet and weeping.

The thin pipe shown above is the source of the newly discovered leak. This is where the pipe tucks under the acoustic cover to connect to the exhaust cooler.

Two more views from under the front of Hx looking at the steering gear and undertray. 

The extent of the leak can be judged from the staining on the components. At first glance, it would seem that the steering box has sprung an oil leak.

Only yesterday when I replaced the engine acoustic cover, I noticed that the hose which connects to the upper outlet on the exhaust cooler had somehow moved closer to the nearby spinning fan blades. There was no obvious signs of leakage but with a weird sense of premonition I recall thinking it was about to give up as I secured it back up under the cover.

And there is history of this happening before...

When ownership began years ago, the first issue was a coolant leak from the very same section of pipe. I recall at the time being surprised that this section of pipework was made from thin wall plastic that given time and temp just goes brittle and cracks. It is a known trouble spot on the Td5.

Back then, I repaired it by cutting out the affected section and replacing it with suitable rubber hose. That repair lasted till today.

Now, rather then just repair this section of pipe again, I propose to drain down the cooling system and remove the exhaust cooler plumbing completely. This will require some fabricating of a suitable hose to by-pass the cooler and maintain the integrity of the engine cooling circuit. 

Also, it will make sense to renew the OAT coolant. It has a 5 year life which is well overdue for replacement.

DRAINING THE COOLANT..

This view, looking up from beneath the front of the engine, shows the circular access cover removed from the undertray. The bolt head visible is the drain plug for the cooling system. Its a 13mm bolt and the pipe is metal at this point.

I mainly followed the Rave procedure for draining the engine coolant, although I left the reservoir cap on till the drain plug bolt was removed to try to stem the rapid flow. The 13mm drain bolt was very tight and I had to use a big breaker bar to crack it loose.

I used a large drip tray to collect the antifreeze as I wanted to measure just how much came out. In the end just under 7 litre drained out. 

COOLANT TYPE AND CAPACITY .

Td5 engines use red coloured OAT antifreeze. OAT stands for Organic Additive (Acid) Technology. It offers better performance and protection then the blue ethylene glycol variants and it has a longer working life. 

The two formulations are not compatible and must never be mixed together as the outcome can produce a kind of chemical jelly.

Rave gives two figures for the engine coolant capacity. 8 litres for a refill and 13 litres if filling from 'dry'..? I am assuming the 13 litre figure is what the factory originally put in and the 8 litre figure is for service intervals like now. The dilution is 50% and as I have 5 litre of concentrate that means I have 10 litre max.

Mentioned earlier that I drained nearly 7 Ltr from the system. Reckon that means Hx lost over a litre to the 'leak', I recall the coolant reservoir level was well below its normal level and it will be interesting to see how much goes back in!

BY-PASSING THE EXHAUST COOLER .

In a previous post 'Cleaning up the EGR Removal' I outlined my intent regarding the exhaust cooler plumbing and gave some background into doing so. I will concentrate here on the hose fabrication after a little re-cap...

This is the exhaust cooler from a Td5 15P engine. It is mounted to the front of the cylinder head. Two hose connections are shown, the lower one is the inlet and is of normal rubber construction. The upper connection (still attached in above photo) is the outlet that routes to the coolant tank. This pipe is a hybrid of rubber and thin-walled plastic and is prone to leaking.

I had already replaced a section of the plastic pipe that had failed on Hx, but I have to report that the same section (rubber this time) has failed again causing the current leak.

Here is the location of the current leak. This pipe can be seen in the first photo of this blog.

Clearly something has been rubbing against this pipe and causing the hole to appear on the left. It is just a 'pinhole', but heat and pressure will inevitably do its thing.

I wrote earlier about the possibility of contact with the nearby fan blades, but it could also have been rubbing on another component. Either way it has resulted in taking Hx off the road.

FABRICATING A NEW HOSE

Time to delve into the bag of bits ..

From the above chaos, comes some order. Have to admit that I really enjoy dickin around with this sort of thing. Lots of time spent looking, planning, and test fitting finally arrives at the solution!

This is the 'new' coolant hose custom designed and fabricated to by-pass the exhaust cooler on the Td5 engine. All the bends and turns are 'natural' and chosen on purpose.

All components are from the spares bin including the in-line plastic connectors. These actually came from the hoses that were removed from Hx.

  

They are a tight fit into the small-bore hose, but I had to leave the 'stump' of the original hose on the fluted end of one of the connectors in order to get a tight fit into the larger bore hose. 

The finished hose, still in two parts but with clips and connectors fitted.

Close up of the connection where the internal bore size changes. This change of bore size mirrors the original install which also uses pipes of differing bore sizes. I would like to know why this is so? Maybe it is down to fluid dynamics and the need to make sure that the flow rate is maintained?

FITTING THE NEW PIPEWORK.

First connection is to the end of the metal pipe that runs around the back of the engine block.

Tracing the path of the original exhaust cooler supply hose will reveal this location beneath the fuel cooler/ inlet manifold. The thicker end of the new pipework easily connects here and directs the flow upward towards the Coolant Reservoir. The thinner section of pipework then connects direct to the Coolant Reservoir itself.

This new pipe run was easily fitted to the engine. I tried to take some photos of it fully installed on the engine but it is difficult to show clearly in a photo.

REFILLING THE COOLANT.

Rave recommends to flush the system with running water once it is drained down. I elected not to do this fearing it would only dilute any remaining coolant that was left inside the engine and therefore dilute any new solution that would be added.

I am a bit confused by the Rave figures of 13 litres for the 'dry' capacity and yet only 8 litre for the refill..? 

That would seem to suggest that only 8 litres will drain out of a previously filled cooling system. I was careful to collect the drained coolant from Hx just to see how much came out as well as look at its condition. In total just under 7 litre was drained out but that doesn't account for the leaked volume. So its safe to say that without the leak I would have drained out 8 litre.

Before re-filling commences the drain plug has to go back on. I wrapped a couple of turns of PTFE tape onto the threads and torqued it hand tight for now.

There is a vent plug that needs to be opened on the top radiator hose during the refilling procedure. Rave recommends that coolant is added to the reservoir until it emerges from this vent. 

Curiously, Rave also recommends raising the physical level of the reservoir by 4 inches during re-filling. It will just unclip from its position and it is important to refill the system thus. I can only assume it helps to remove any air pockets internally?..

I used a one litre water bottle to mix the coolant and water in handy litre measures. Use of a small funnel helped to avoid spills. 

I filled the reservoir up to its maximum level without any fluid emerging from the vent hole. I then started the engine and shortly after that the coolant emerged from the vent hole. I quickly tightened the vent plug up to stop the flow. I then stopped the engine and checked all the new hose connections for leaks. 

The level of coolant in the reservoir had dropped again so I topped it back up to the max level and went for a little drive to warm the engine up and re-checked everything again.

Pleased to say there are no more leaks.

The level will be checked and topped up over the coming days just to be sure, but things are looking good so far...

UPDATE : The next day I checked the reservoir level which had dropped slightly and topped it up with the remaining mix from the other day. This means in total 7 litres of coolant were replaced in the engine.

All the new hose connections and the drain plug were dry. I will check again in a few days before striking this off the 'to-do' list.

see also  -  ' Td5 EGR / Cooler removal '