Thread: TD5 Cracked Block - Looking for Donor

Originally Posted by V8Ian

Is the car using coolant?

It was before I replaced the head but only seemed to be from the fuel cooler which I fixed with new O-rings but it did get a little hot on very hot days and when I was pushing it up hills - egts would climb rapidly - if I backed off on the gas temps would drop just as rapidly. Coolant system would be on the verge of boil with a few traces coming from over flow - Madman temp sensor that I carefully calibrated would get as high as 106C up hills but as I say would also drop in less than 2 minutes back down to the 90s if I backed off the gas. I always felt that it was some kind of over fueling causing the high egts. And yes I do have a remap and yes putting it back to stock did reduce this effect a lot, however the guy that did the remap has very reputable on this forum and he reckons what he did to my map would not cause that.

I have wondered about the injectors but the engine runs very smooth and Nanocom balance is just 1-3 across all cylinders. If I had one or two over fueling injectors I would expect this to show up on the balance.

Originally Posted by PhilipA

Did you look carefully at all the cylinders when you had the head off?

I did look but not that much because I didn't think I had a problem in there because my compression was good 430PSI on every cylinder before I replaced the head.

Originally Posted by PhilipA

To have high crankcase pressure I would think that the crack would have to be in a cylinder. I guess there could be a crack between the cooling system and crankcase itself but this should not cause high crankcase pressure just goopy oil and an increase in oil/water level.
If the temp stayed under 100C then the water should stay as water and the oil should be caramel..

Not getting goopy oil or any greyish discolouration but there is evidence in the oil lab test results indicating coolant - I was thinking if it was exiting via a crack in the block as hot boiling coolant vapor it would boil off as steam (as you say over 100C) however I am doubting this now. Previously when I was driving it around the average coolant temp was mostly pretty normal around 93C except when I put my foot on the gas and especially up hills.

Originally Posted by Max Headroom 2.3m

It would be good to prove that the vapour is in fact coolant based.

Yes this something I am still trying to prove/verify!

Originally Posted by Max Headroom 2.3m

I am not aware of any labs that test crankcase vapour for coolant contamination but there appears to be tests available that detect coolant in oil (e.g. Atomic Emission Spectroscopy). Perhaps one of these tests could be adapted for your application. Maybe a phone call to a lab that tests oil and discuss.

As for sample collection, I imagine that the crankcase vapour could be bubbled through a clean and rinsed glass container of distilled water which would dissolve and concentrate any coolant products present. The longer you bubble through the more coolant products would concentrate if present. This is thinking outside of the box and novel as far as I am aware so not sure if this is worth a try. A negative result would not rule out but a positive would confirm.

Good food for thought, thank you!

Originally Posted by Max Headroom 2.3m

Another thought, I assume you have confirmed that there are no blockages down stream of the camshaft cover outlet e.g. blocked Provent filter or PCV (if still used). I believe newer Provents no longer bypass to atmosphere with a closed system.

Originally it blew the silicone hose off the provent filter when it first happened and continued to have positive pressure vapour pouring out of the hose. I have nothing connected to the PCV port on the cam cover at the moment.

Originally Posted by TAHAIC

Originally it blew the silicone hose off the provent filter when it first happened and continued to have positive pressure vapour pouring out of the hose.

If it is water/coolant vapour coming out of the cam cover port then it would seem logical for the vapour moisture to mix with any oily residue in the Provent filter, creating a goopy layer on the filter surface and thereby blocking the filter. This, however, shouldn't cause the hose to blow off as there should be a safety valve built into the Provent lid (old version) or in the base of the filter cartridge (new version) assuming we are talking Provent 200. I find it odd that the hose blew off. Have you tried blowing down the cam cover breather hose into the Provent to prove it is blocked. Maybe also check the filter to see if it is covered in creamy goop although it may not be obvious if in the filter matrix.

In an attempt to prove it is water/coolant vapour coming out of the cam cover, it might be worth bubbling the vapour through a small amount of clean oil in the bottom of a clean glass jar (I seem to have a thing for bubbles and glass jars...don't ask!). I would expect it to turn milky/creamy. Perhaps confirm this first by trying it with steam from a bit of hose from a boiling kettle to see how obvious it would be.


I have to say that your diagnostics so far seem logical and your descriptions are pretty detailed. I wish I could be more helpful but I am scratching my head a bit on this one.

Originally Posted by Max Headroom 2.3m

If it is water/coolant vapour coming out of the cam cover port then it would seem logical for the vapour moisture to mix with any oily residue in the Provent filter, creating a goopy layer on the filter surface and thereby blocking the filter. This, however, shouldn't cause the hose to blow off as there should be a safety valve built into the Provent lid (old version) or in the base of the filter cartridge (new version) assuming we are talking Provent 200. I find it odd that the hose blew off. Have you tried blowing down the cam cover breather hose into the Provent to prove it is blocked. Maybe also check the filter to see if it is covered in creamy goop although it may not be obvious if in the filter matrix.

In an attempt to prove it is water/coolant vapour coming out of the cam cover, it might be worth bubbling the vapour through a small amount of clean oil in the bottom of a clean glass jar (I seem to have a thing for bubbles and glass jars...don't ask!). I would expect it to turn milky/creamy. Perhaps confirm this first by trying it with steam from a bit of hose from a boiling kettle to see how obvious it would be.


I have to say that your diagnostics so far seem logical and your descriptions are pretty detailed. I wish I could be more helpful but I am scratching my head a bit on this one.

Possible to many bubbles through said glass jars 🫠

Originally Posted by Max Headroom 2.3m

If it is water/coolant vapour coming out of the cam cover port then it would seem logical for the vapour moisture to mix with any oily residue in the Provent filter, creating a goopy layer on the filter surface and thereby blocking the filter. This, however, shouldn't cause the hose to blow off as there should be a safety valve built into the Provent lid (old version) or in the base of the filter cartridge (new version) assuming we are talking Provent 200. I find it odd that the hose blew off. Have you tried blowing down the cam cover breather hose into the Provent to prove it is blocked. Maybe also check the filter to see if it is covered in creamy goop although it may not be obvious if in the filter matrix.

In an attempt to prove it is water/coolant vapour coming out of the cam cover, it might be worth bubbling the vapour through a small amount of clean oil in the bottom of a clean glass jar (I seem to have a thing for bubbles and glass jars...don't ask!). I would expect it to turn milky/creamy. Perhaps confirm this first by trying it with steam from a bit of hose from a boiling kettle to see how obvious it would be.


I have to say that your diagnostics so far seem logical and your descriptions are pretty detailed. I wish I could be more helpful but I am scratching my head a bit on this one.

The Provent filter is not blocked or anything - its relatively new. The problem is silicone hoses are really slippery, I even used T-bolt clamps for all my silicone hoses and I used silicone because of the heat on the exhaust side. Actually have to say rubber hose is better as it is not slippery. All of your thoughts concerning water mixing with oil are justified and I tend to agree, however I am not finding any greyish goop forming. I am also not detecting any CO2 exhaust gas in the vapour - its very puzzling.