Checked my oil before a big journey the other day and spotted emulsion under the oil filler, looked in the coolant tank and it is black, although no emulsion or floating oil.

No obvious difference to driving, and no warning lights on.

 

First thoughts were head gasket, or cracked head, or maybe oil cooler. Either way I got a hire car for that trip and am only just able to start thinking about fixing it.

 

Called my local garage, who have really evolved from a body shop and are really good with other aspects of car repair, to see if it was something they could deal with, they said to bring it in and they could have a look. That didn't go too well, basically said all they could do is throw parts it and recommended I just monitor it to see if it gets worse. I asked if they could compression test it for a clue, and he didn't even know if they have a diesel compression tester. As it happens, I have diesel compression and leak down testers and have done my own head work on my van engine in the past, but things change and I really don't think I have the time or inclination to tackle it myself at this time of year. I may have to if I can't find a garage that seems to know what they are talking about with engines.

 

I'm really thinking on 2 fronts now:

- Does anyone know of a garage in Dumbarton or surrounding areas that specialises in engine work (and understand diesel engines)?

- Does anyone have experience compression testing or taking the head off these engines? I have only had a cursory glance but can't see where the glow plugs are which suggests it is going to a pain to rig the compression tester, if I even have the right adapter. I'm probably not going to be able to position it where I can see the dial myself either. I assume taking the head off means taking the injectors and camshaft off and all the usual faff that normally drives the labour time up, I'll bet I don't have the right timing lock tools for this engine either. My instinct unless the gasket is really obviously damaged is to get the head pressure tested too, but the guy I took my van head too has since retired and shut up shop.

 

Has anyone had a head gasket changed by a garage recently and have some idea of the basic cost?

and/or had a head pressure tested? (where?)

and/or had a recon head fitted?

 

 

I would use one of the combustion gas in the coolant testers, the ones like this on ebay:

 

https://www.ebay.co.uk/itm/COMBUSTION-LEAK-TESTER-KIT-CO2-PETROL-HEAD-GASKET-TEST-FLUID-BLOCK-50-TESTS/323563168415?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m1438.l2649

That would be a good place to start, presence of exhaust gas in the coolant would at least rule out the oil cooler.

If it does have exhaust gas in it  I would still need to do compression test to indentify likely cylinders and try a leak down test to see if I can work out roughly where the leak is (that is really difficult, I'm probably not up to that!)

 

Thanks

29 minutes ago, Jim-octavia said:

...basically said all they could do is throw parts at it and recommended I just monitor it to see if it gets worse

That is what 99% of garages do. Replace parts (on the expense of the client) and hope the problem will go away.

Now, about the leak combustion tester kit. My experience on it combined with many other users' opinions on forums and YouTube make me say the results are doubtful. You can't tell for sure if a real problem exists. The only correct test is a leak down cylinder test. Black coolant is proof of an oil leak. Where exactly the leak is located involves a very thorough analysis in a garage. Tell them to quit guessing and start thinking.

Edited 13 December, 20196 yr by RicardoM

Just remove the expansion tank cap when the engine is stone cold.  If there's a hiss of escaping pressure, it's almost certainly due to combustion gases getting into the cooling system.

Free test, easy test.

4 minutes ago, RicardoM said:

That is what 99% of garages do. Replace parts (on the expense of the client) and hope the problem will go away.

Now, about the leak combustion tester kit. My experience on it combined with many other users' opinions on forums and YouTube make me say the results are doubtful. You can't tell for sure if a real problem exists. The only correct test is a leak down cylinder test. Black coolant is proof of an oil leak. Where exactly the leak is located involves a very thorough analysis in a garage. Tell them to quit guessing and start thinking.

 

I agree, that's exactly why I am looking for a garage recommendation as top priority.

I would think not finding exhaust gas in the coolant doesn't definitely rule out a gasket leak, only that finding it indicates that you have that or worse. Probably a useful thing to do as well as compression and leak down, but limited value on its own.

To do a leak down test effectively takes experience, I have tried to do it myself before and struggled to interpret what I was getting, so would rather find an experienced mechanic than take it on myself again. Admittedly when I took that head off and had it pressure tested the guy found a crack between ports which may be why I couldn't pin point where it was leaking.

At least these guys are honest enough to admit they don't know how to test it and not take the job on!

42 minutes ago, Wino said:

If there's a hiss of escaping pressure, it's almost certainly due to combustion gases getting into the cooling system.

The cooling system is pressurized by design. An airtight cooling system holds pressure also when it is functioning properly. So there is a pressure relief (a hissing sound) when opening the cap of the reservoir anyway. Now, if combustion gases are present, a bigger hiss is expected. Moreover, the cooling rubber hoses are very stiff. In reality very few cooling systems are airtight so the pressure slowly decreases. That is, normal pressure or combustion gases pressure.

Also let's not forget that if the coolant is black and there is an emulsion under the oil cap, there is a leak between the lubrication system and cooling system. This means there are no gases involved.

It's only pressurised by thermal expansion, so isn't when cold.

How much emulsion was there under the oil cap? A small amount can be normal, I've had it plenty of times and no HGF.

 

Are you losing any coolant? Any sign of the oil level rising? How long has the coolant been black for?

Not having much luck finding a decent garage locally that aren't too busy, the ones people have recommended are either too busy to look for another week or closed for the holidays. At this rate I can have the job half done before I can even get it looked at...

 

Decided to do a compression test at the weekend, opened my tester to find that on the back of the sheet for my Vectra I had written Octavia and a date back in May, but there were no numbers - is my memory really that bad? Quick think, vague recollection of not being able to get the tester on..., open bonnet and take top cover off find glow plugs and it all came flooding back! The channels the glow plugs are installed in are too narrow for the right angle fitting in my test kit to slide down so I can connect the coupling to the glow plug adaptor. Quick session on the grinder and the right angle fitting now fitted, but the coupling thread was a bit loose when putting it back together so I wrapped some PTFE tape around the thread, and then snapped it off in the right angle fitting. So no compression test, new coupling on order.

 

Interestingly because I did remove all the plugs ready to do the test, No.1 glow plug had much greater carbon deposits than all the rest, in fact I had to carefully work it out. And then I remembered why I had tried compression testing in May - VCDS was telling me I had open circuit on the plug circuit so I had changed them, and figured I might as well get a baseline whilst the plugs were out. So the plugs are 6 months old and No.1 is significantly carbed up. This is a clue I will be storing away for future use, I will not be at all surprised to learn that No.1 is down on compression when I finally get my act together!

 

I have had a quick read through of Haynes and it looks like getting the head off should be reasonably easy on this engine, looks like it can come off with camshaft in place (on my Sprinter I had to take the camshaft off to get to a third of the head bolts, and then reassamble it for pressure testing, then dis-assamble again to refit, and finally put it back all back together.

 

See what exhaust and compression tests show first, still an outside possibility it is only the oil cooler...

On 13/12/2019 at 10:28, Jim-octavia said:

Has anyone had a head gasket changed by a garage recently and have some idea of the basic cost?

No, but I'm in Dumbarton for Xmas. Note me a phone number and we can arrange to meet up and I'll have a look.

1 hour ago, KenONeill said:

No, but I'm in Dumbarton for Xmas. Note me a phone number and we can arrange to meet up and I'll have a look.

Thanks for the offer, I am however supposed to be in Norfolk by Xmas...

11 minutes ago, Jim-octavia said:

Thanks for the offer, I am however supposed to be in Norfolk by Xmas...

No problem; I'm literally in Dumbarton right now. The first point with mayo is to determine whether not the engine is running cool, like my uncles' Hillman Avengers used to do...

Why not try the test I suggested, it takes no time and has no cost?

It's pretty well established in the mk1 Fabia forum, have a search.

Still struggling with cheap diagnostic tools, but getting closer!

 

KenONeill - engine gets up to temperature easily within about 10 minutes driving at 30 and 40, would be quicker if I could get to the dual carriageway quicker!

 

Wino - I subconsciously do your test every time I open the coolant cap, it is more of an observation than a test and I think it would be quite unusual for an exhaust gas leak into the coolant to keep the coolant pressurised when the engine is cold, if there was a leak, well it is a leak, so the pressure would leak back out when the engine is off. If it is pressurised, there is some kind of big problem, but if it isn't pressurised, there might be a problem.  Anyway, I took the cap off with the coolant still quite warm to do the coolant test and no pressure.

 

Also tested negative for exhaust gas, even when I re-ran the test. But even that isn't conclusive, the instructions list lots of reasons the test can show negative. Also shining a torch into the header tank I spotted that the coolant isn't black at all, its dark blue, which is the colour it should be - no oil contamination in the coolant, apparently only coolant in the oil.

 

The coupling for my compression tester arrived today. Decent quality unlike the cheap one it came with. 3 out the 8 adapters (including the one I needed) didn't couple properly, my caliper showed the groove on these 3 was 0.2mm bigger diameter than on the 5 that fitted. No problem, stick the collet chuck on my lathe, and quickly I had the adapter I needed fitting the coupling, and the engine was still warm, although cooling. (I later tried to turn down one of the other adapters and it snapped, crappy chinese brass!)

 

Connected up to cylinder 1, turned the engine over, compression built up OK but the needle wasn't holding, switched off and it dropped to zero, so the NR valve in the adapter must be jiggered. After some more trials I ended up tying the gauge to the bonnet with a torch shining on it and using my phone to video the gauge whilst I turned the engine over. 1 and 2 made about 22bar fairly easy, 3 was struggling but seemed to get there, by the time I got to 4 I could hear the starter was struggling and I can't even tell what the maximum reading was from the video, might have been 22 but it was dropping further between strokes and really hard to see. Haynes say minimum 19 bar with no more than 5 bar difference between cylinders so might be OK, but I'd be happier if the gauge was holding the readings so I could check them properly!

 

I have now worked out that the adapters basically have a schraeder stem inside them, so I swapped the duff one with another one, but clearly there isn't enough in the battery to test again tonight, so I'll start again tomorrow from 4 backwards and see if I can get decent results.

 

There is a chance this will turn out to be nothing (or the oil cooler), but I'd like to get to that conclusion by proper diagnostics, I'm just a bit annoyed that I couldn't find a garage who could look at it this week, because with decent equipment it would have taken about 30 minutes to do the tests I am now the best part of 6 hours into and still going!

Check the engine temperature (actual, not gauge); the actual should be hitting 90C and staying there in about 10 minutes.

10 hours ago, Jim-octavia said:

I think it would be quite unusual for an exhaust gas leak into the coolant to keep the coolant pressurised when the engine is cold, if there was a leak, well it is a leak, so the pressure would leak back out when the engine is off

 

Not really, unless you assume the extreme temperatures and pressures in the combustion chamber have no effects on the gasketed joint...

 

Anyhoo, looks like you don't have such troubles, or perhaps any. What oil are you using? Some are worse than others for emulsion formation.

 

 

6 hours ago, KenONeill said:

Check the engine temperature (actual, not gauge); the actual should be hitting 90C and staying there in about 10 minutes.

Well it sits at 90 on the gauge so I didn't bother looking in VCDS, I'll maybe double check that tonight.

23 minutes ago, Wino said:

 

Not really, unless you assume the extreme temperatures and pressures in the combustion chamber have no effects on the gasketed joint...

 

Anyhoo, looks like you don't have such troubles, or perhaps any. What oil are you using? Some are worse than others for emulsion formation.

 

 

I mean there are a lot of different possible routes and levels of leakage etc. I do have experience of head problems that change with temperature (crack in Sprinter head) but it seems like something that would only happen in few cases. Anyway, it isn't happening to me!

 

Oil is Comma Xflow type V which is their claimed 507 00 equivalent. I have always used comma oils because that is what my local motor factor supplies, maybe the type V is more prone than their other formulations?

@Jim-octavia

Does the car run OK?

When was the oil & filter changed, how many miles ago,

and how long are the daily trips?

 

When was the coolants strength checked or the coolant changed?

 

Is the Air filter totally dry, and have you been driving much in heavy rain or wading through water.

Are all breather pipes / intake pipes in good condition?

???

Have you had the car long enough to know that Rad-Weld or the like has never been used?

Edited 18 December, 20196 yr by Roottootemoot

25 minutes ago, Jim-octavia said:

Well it sits at 90 on the gauge so I didn't bother looking in VCDS, I'll maybe double check that tonight.

I've never 100% trusted the gauge since I discovered it's programmed to read 90 when the actual water temp is anything from 60 to 105. You have a fault narrative that could be mayo resulting from a stuck open thermostat.

2 hours ago, KenONeill said:

I've never 100% trusted the gauge since I discovered it's programmed to read 90 when the actual water temp is anything from 60 to 105. You have a fault narrative that could be mayo resulting from a stuck open thermostat.

That's news to me, seems little point having the gauge at all if thats how it is set, may as well just make it a high limit warning light! If true it does explain why it never seems to vary once warmed up!

I will definitely confirm with VCDS later!

 

No other thermostat symptoms yet, usually can't get decent heat out of the heater if the stat is stuck open and I can still get mine to blow like a furnace, but won't rule it out until I've confirmed that the ECU thinks I'm getting 90.

3 hours ago, Roottootemoot said:

@Jim-octavia

Does the car run OK?

When was the oil & filter changed, how many miles ago,

and how long are the daily trips?

 

When was the coolants strength checked or the coolant changed?

 

Is the Air filter totally dry, and have you been driving much in heavy rain or wading through water.

Are all breather pipes / intake pipes in good condition?

???

Have you had the car long enough to know that Rad-Weld or the like has never been used?

The car runs fine, fuel economy was always a bit less than expected but is OK (had it since Oct 2018 with 130k miles, now nearly 150k miles), the DMF rattles like hell at idle but it is quiet and pulls well when it is going. No change there.

 

I'd need to check in VCDS how far since I reset the SRI, I remember the warning came on (500 miles?)  about a week before I drove to Spain at the end of May and I figured I should probably do the service before I went because it would be further than the mileage I had left! Must be 10k miles ago or more.

 

Daily trips a couple of miles, a 40 mile round trip once a week and until a month ago weekends are generally 200 - 1000 miles depending on where I am racing, so the mayo did first appear just after the long trips eased off.

 

No idea when or if the coolant has been changed, disc tester shows 5 discs (max strength), just re-checked to be sure. Likewise no way to know if radweld has been used, but no mayo for a year and 20k miles...

 

I have been thinking about whether it could be from the intake, I live in Scotland and I'm a canoeist, of course I drive in heavy rain, and often through 'surface water' (WTF does that mean anyway, sub-surface water is not a problem, aerial water is not a problem for traction only visibility, would it really be too ambiguous to call it 'water' or 'puddles'?).

There was an issue with an intercooler pipe with a broken lug that had been wedged in place, but I replaced that and it seals properly now. If I was getting water into the inlet, surely it would tend to condense in the intercooler and not reach the manifold? Unless the intercooler is saturated? It has been biblically wet this summer! I haven't checked any of this, but will.

Water doesn't need to come from outside the engine to create mayo, the engine makes its own as part of the combustion process. 

Hydrocarbons plus oxygen makes CO2 + H2O (vapour initially), mostly.  Any combustion gases that get blown by the piston rings will condense water out into the oil until the oil is hot, and can build up there if the engine doesn't get hot enough, for long enough, each drive cycle. 

13 minutes ago, Jim-octavia said:

so the mayo did first appear just after the long trips eased off.

That seems consistent with it being simply down to shorter trips.  Re-check it after the next 40 mile trip.

 

 

Edited 18 December, 20196 yr by Wino

Just my two-pennies worth.

 

Mayo on the underside of the oil filler cap is relatively common, more so on petrol engines than on diesels in my experience, but at this time of year, especially after several short journey's it might not be anything sinister?