Lack Of Oil To Turbo

[Bert66]

As the title says I've just fitted a new turbo to my C4 1.6 hdi and one of the last jobs is to measure the flow of oil through the turbo. In one minute at idle it should be at least 300ml but the best I am managing is just over 200ml.

Now, this would indicate a sludged up engine but the odd thing is, when I removed the sump, there was no sludge whatsoever in the bottom, nor was there any indication of sludge in the oil strainer, vacuum pump or gauze in the bottom banjo bolt (which I've now removed). I also removed and checked the oil pump which was similarly sludge free.

The injectors show no sign of carbon build up round the seals and all the bolts securing them were tight although I've not stripped the top of the engine.

 

So, I'm a bit stuck. Could an engine suffer a oil restriction like this without any indication of sludge on the bits I've checked/cleaned? If so, where could the blockage be and more importantly, how could I clean it bearing in mind that I ran three lots of flushing oil through the engine before I started.

Alternatively, despite looking pristine, the oil pump might be the culprit but where would I connect a pressure gauge to test it and what should it read?

Any other suggestions gratefully received!

[mhedwig]

Connect an oil pressure gauge where the oil pressure switch goes on the filter housing

[paul.h]

Looking in the Haynes manual it gives the minimum oil pressure for oil at 80°C (110°C in the Citroen service box procedure after checking the oil level) as 1.3 bar at 1000 rpm and 3.5 bar at 4000 rpm. This would also depend on the oil being used. If you are measuring the flow with cold oil it will likely change as the oil heats up and becomes less viscous. Citroen's procedures show an oil filter cover being used with a pressure gauge tapping on it, so pressures measured here may be a bit different to ones at the pressure switch.

[Bert66]

As an aside, I've fitted a turbo oil feed pipe with an inline filter which is much larger but a finer gauze than the little one I removed from the banjo filter. I suppose it's possible, that with cold oil, it may restrict flow a bit. On Monday I'll call the chap who I bought it from and ask.

Running the test a couple more times tonight it was noticeable that oil coming out was dirty which I guess could shows the flushing oil didn't get everything. It's just odd that the bottom of the engine was so clean. If the top half is still restricting oil how the heck could I clean that - remove the head?

[paul.h]

I think you are not supposed to fit another filter to the banjo bolt when you replace the turbo, just remove the old one. If the new one has smaller holes than the old then it is even more likely to block, as well as give a higher pressure drop and reduce the oil flow (which may be off set by the larger filter).

[Bert66]

The purpose of this larger filter is that I can regularly remove it and check it so although it may catch some crud I should be able to remove it before it gets anywhere near being blocked. As for reducing the flow I wondered that so I removed it for a test this afternoon and it didn't seem to make any difference to the oil delivered in 60 seconds.

Someone has pointed out to me that the oil is delivered to the turbo straight after it goes through the oil filter ( which I removed the housing and cleaned along with the cooler although neither was dirty) so I'm not sure there could be a blockage there.

 

Could there be a restriction in the head? Other than that it points to the oil pump but as I said it looked fine when I removed it.

[Bert66]

Well, I spoke with both the guy who I bought the modified pipe from and he very helpful. His particular view was that, if after cleaning and checking as I did on the engine, if there were 200mls flowing through the turbo with cold oil then he didn't necessarily see a particular problem as the turbo bearings are being supplied a constant quantity of oil.  He was far more concerned in avoiding any carbon deposits reaching the turbo bearings.  He did however put me onto a turbo specialist for a second opinion.
I spoke with the turbo people and their view was that with everything I have checked or changed, a blockage seems very unlikely.  In fact, blockages with reference to this engine generally means of one of the filters the oil passes through and not an actual oilways.
They did however, quote the 300ml figure but the chap I spoke to couldn't confirm that this figure should be with warm or cold oil.

During these conversations, it jogged my my memory that on the cartridge I removed, I could see the turbo shaft through the oil inlet hole.  On the replacement I'm sure (but I now need to check) that I couldn't see the shaft and it was difficult to pre charge the bearings with oil because the inlet hole narrowed at the end into a smaller hole.  If this is the case then it may be that this restriction is the cause of the problem.  I've called the manufacturer but they're out at lunch and are going to call me back.  I've also just thought that I don't think the instructions with the cartridge specified the oil flow test.
 Could be promising :-)

[Bert66]

Having now checked the old turbo cartridge, it to has a narrowing on the oil input hole ( I must have looked at the shaft through the outlet).

Added to which the oil pump is now leaking so I'm going to have to remove it again. At this point I think I might as well just replace the pump. There is then nothing left I think I can do, if a new pump doesn't improve the flow I'll have to live with what I've got.

[paul.h]

Thanks for keeping us up to date, we are all learning from your experience. I looked in the Citroen service box procedure for turbo replacement but could not find anything on checking the oil flow unless there is a Technical bulletin, but it does say to remove the banjo oil strainer. Where did you get the info from that the oil flow should be 300 ml/minute ?

[Bert66]

I found the 300ml figure on the Internet (might have been the Berlingo forum) but it cropped up a couple of times. It never was explicit about whether it was with a hot or cold engine though. It was interesting that the guy I bought the modified pipe from was much more concerned about carbon deposits in the oil rather than the volume of oil itself ( hence why he fits his modified pipe to any turbo replacements he does).

It does beg the question, how much oil do they need; 200ml, which I was getting, is a small mug full, per minute, at idle to lubricate 2 relatively small bearings. At 2000rpm this would increase significantly and I presume a major component of the oil flow is then to cool the bearings.

Either way, I'm not convinced that 200ml is inadequate and once I've replaced the oil pump, there's really little else I think I can do other than keep and eye out for any deposits in the inline filter.

 

I do have one question though: I refitted my old oil pump and it's now leaking. There didn't appear to be any seals or sealant on the mating faces when I took it off and I didn't apply any when I refitted it. Should I have done?

[paul.h]

When refitting the oil pump, the C4 Haynes manual (page 2C.17) says a 4mm wide bead of sealant should be applied to the cylinder block mating surface and the oil seal on the pump should be replaced. It says new oil pumps include the new seal and it has a protector sleeve so it is not damaged when fitting over the crankshaft. For the cost of a Haynes manual it may be worthwhile getting one or look in your local library to see if they have a copy.

 

One thing about a strainer that needs to be considered, it may not block up gradually so frequent checks may not prevent a sudden blockage.

[Bert66]

After fitting a new oil pump, I've finally finished the job. Just to recap, my turbo failed at 58000 miles and along with its replacement I removed the sump, checked the sump filter, vacuum pump filter, banjo bolt filter(removed) and oil pump for signs of swarf or sludge of which there was none.

 

I refitted everything but replaced the turbo oil feed pipe with a modified one that had an in line filter that can easily be checked for oil contamination. I also pulled out the recessed sump plug so that all oil is removed at a change.

 

The oil flow test revealed just over 200ml per min flowing through the turbo rather than the oft quoted 300ml. This test also revealed the oil pump was leaking so the pump was replaced with a new one which may improve flow (but I haven't checked).

The last job of refitting the auxiliary belt was impossible using the Sealey tool I bought but was a 2 minute job to do with a helper.

 

I never did really fathom why the turbo failed but if it goes again I think I'll get shot of the car.

 

Finally, thanks to those that have helped me through it on here and I hope my experiences can now help others in a similar boat.

[paul.h]

The 1.6 hdi is known for early turbo failure but it could have failed due to not having the correct oil or maybe the previous owner has abused it by not letting the engine warm up/oil circulate before revving the engine on starting and by not letting the engine idle for a while before switching the engine off so the turbo is still spinning but the oil supply is stopped as the engine stops.