Inlet mainfold rubber hoses

[#84]

I searched the forum for info about how to change the 4 rubber houses connecting the inner and outer parts of the intake runners. I found one old thread giving some hints of how to get them off, so if anyone who is active now have more info to share I would appreciate it a lot. What I have in mind is:

- How on earth do you tighten the clips again after replacing the hoses?
- The local very experienced Alfa Romeo workshop recommended me to go for aftermarket silicone hoses. Comments?
- Pictures of the disassembly process would be just great!

[wrinx]

This might help a little:

http://alfa155.org/forum/viewtopic.p...8773&start=300

If the clips are the usual horrible Alfa things I just stick a screwdriver in and twist them off, then replace with jubilee clips! When replacing, make sure you put the worm drive on the upside to make them more accessible.

On mine, the clips had been replaced with jubilees but the idiot before me had put the worm drive underneath which meant I had to remove the throttle body and squeeze my arm through the tiny hole to get at each one...I was COVERED in buises!

Alfajack has done this job a few times and may have more advise...my parting comment is to be aware of the earthing straps at the rear, unless you undo them they will prevent you from removing the inlet until you break them!

wrinx

[Steve Webb]

When my engine got rebuilt before I got the car, the clips were replaced by jubilee clips but unfortunately they rebuilt the whole thing on the bench so the clips are at a bitch of an angle to get to.
I do want to get the manifold off at some point, when I eventually get the car back from the garage and back on the road, as I'm swapping over to the Integrale manifold.

[AlfaJack]

I searched the forum for info about how to change the 4 rubber houses connecting the inner and outer parts of the intake runners. I found one old thread giving some hints of how to get them off, so if anyone who is active now have more info to share I would appreciate it a lot. What I have in mind is:

- How on earth do you tighten the clips again after replacing the hoses?
- The local very experienced Alfa Romeo workshop recommended me to go for aftermarket silicone hoses. Comments?
- Pictures of the disassembly process would be just great!

- How on earth do you tighten the clips again after replacing the hoses?
Once you have the jubilee clips on then you can, as advised above, get a screwdriver down. I find the easiest way is to remove the inlet pipe that runs beside the battery and then the 90 degree rubber pipe. This allows you to get your arm under the inlet to hold the clips whilst you undo them.

- The local very experienced Alfa Romeo workshop recommended me to go for aftermarket silicone hoses. Comments?
I doubt they are available, other than straight pipe of silicone pipe - the originals are stepped at each end to provide a tight seal.

- Pictures of the disassembly process would be just great!
As mine is in pieces like this at the moment, I'll get some good pics over the weekend.

[wrinx]

There are stepped silicone hoses available but you'd have to cut them down so it's a lot of messing about, the originals are very hard wearing and don't move, so unless they're in pieces I would just put them back on.

wrinx

[#84]

Thank you all for your very quick replies and good input!

The hose for cylinder one is extremely greasy, the one for cyl 2 a little bit. So, I need to replace at least one of them and then I suppose it is best to replace all of them. At least I have to get it all off and check. Even though there is no visual damage, I cannot see any other explanation than a leaking rubber hose for the greasy hose/pipe.

When cold the car runs perfectly, then when it gets hot there is zero idle capability. I had a similar (not that bad) problem back in 2003. A Magneti Marelli specialist in Milan compensated for it by adjusting the throttle position sensor, but I kept on having problems until I late 2007 discovered that one of the gaskets for the EGR pipe flange connection was missing. Amazing. I had checked everything and had it in 4 workshops and no one could identify the reason for the idel problem. The gasket must have been lost when I had it in for a cam belt change. However I believe that one of the intake runner hoses had started to leak by then since I kept having idle problems and fuel smell.

So, when I finally brought out the car 1:st of May this year after many years in the garage, the hot idle problem was extreme and when I slowly tried to rev the engine more and more when the engine was warmed up throughly, the turbo whining was absurd, it sounded like a jet fighter before take off. So, at 5500 rpm it "took off" with a giant blue cloud behind the car

Now the turbo has to be fixed as well, but at least it lead my clearly to the root cause.

[Steve Webb]

It does sound as though getting the inlet off would be a good idea after the car has been stood for that long. Give you a chance to clean things up and get a good look at what might be leaking.

[#84]

First confirmation of my theories was given abruptly sunday morning when the family went shopping clothes, I had a slight hangover and decided to remove the turbo. It went well until I removed the "?-shaped" hose between turbo and IC. The hose and the bottom of the IC was filled with coal black oil pouring out over me .... Around half a liter. I had to interrupt the work while the absorber was soaking up the oil from the floor, all droplets coming out and changing clothes.

[Steve Webb]

Sounds like a failed oil seal in the turbo.

Is it the original turbo in your car?

[#84]

No, not exactely. It is called KRX-400, but is basically a modified KKK K26 which was used on the original Audi RS2 for example. Swedish Turboservice, who do a lot of OEM development and also produces their own turbochargers for WRC (or did at that time) developed it as part of a 400 hp kit for the Volvo S60/V70R back in 2004 something. That is why it has the typical Volvo flange. It didn't give the improvement in spool up and low end torque as I hoped for when I started to look at the Mitsubishi TD04/05 units which were better than the Garrett GT25's, which in turn were much beter than the GT3's they replaced. Therefore it has been modified a few times and the most spectacular part is the minimal ported shroud on the compressor inlet, which was created when we managed to improve the low end boost with several tricks and it instead went into stall in some occasions.

I just got it off the car and the turbine outlet had millimiters of thick semi-coxed oil rests . Other than that and the failed sealings it appears to be in good condition.

[Steve Webb]

Sounds like a strip down and rebuild are in order, but for a failure of that magnitude I'd like to see exactly where the seal failed and why?

[AlfaJack]

Some pics of the inlet off the car:

01_08.jpg

01_09.jpg

01_10.jpg

01_11.jpg

01_12.jpg

[#84]

Thanks a lot!

Now the turbo is sent away for renovation and the boring part remains, but with your pictures I am less scared. Lets just fix the 306 GTI for the race in 1 1/2 week and the Evora for the MOT before the end of October and .. and .. and ..

[#84]

Things appears to turn out somewhat unexpected. I was called last week by the turbo provider who found the turbo to most likely be ok. They should check the sealings in detail to be sure, but meant that normally the bearings are also damaged, which they obviously were not. Block oil return, or high crankcase pressure should be the most likely reason.

So, I leak tested the cylinders (took a while to find out how to turn the engine manually... ;-) ) and then took pictures with endoscope. I checked them before dismounting the turbo and they looked ok. When inspecting every corner in detail I found severe knocking damages at the squish area between the exhaust valves. Where it normally starts. Since at least two, probably all, cylinders leaked a lot at 7 bar test pressure and the exhaust side had these damages, I assume for now that the top piston ring is damaged.

To be continued - how to disassemble in the best way?

[Steve Webb]

For that much oil in the turbo -> Intercooler pipe I'd have thought there would have been something more obviously wrong.

Have you checked on the oil vapour seperator to see if it is full of oil? If the drain was blocked, and all the oil vapour was passed through to the inlet, then I would have thought you would have noticed other symptoms as well.

Seems to be a strange problem as like I said, for that amount of oil it would have expected something more obvious.

You say you've done a leak down test on the cylinders, but have you done a compression test as well? What pressures do you see if you have? It wouldn't be the cause of the oil, but is indicitive of an engine in need of some love. Are you thinking of a complete rebuild?

And as for the stripdown, I think it is fully outlined in one of the manuals on the website. I seem to remember the suggested way of taking the head off, involves bringing the inlet manifold off still connected.

[#84]

I did not have access to a compression test equipment, so I checked what I could with leak down and endoscope. I haven't checked the oil vapor separator yet, but would be surprised if that could freak out suddenly at 5500 rpm and relatively high boost after having driven the car for 25 minutes and roughly 2 hours in total since I brought it out from its rest. In theory, the oil that has been flushed through the system after this event could have been what accumulated in the intercooler at this sudden burst and then just been portioned out in small amounts.

What I think is: At least cylinder one's rubber hose has leaked and caused slow response, hard working - loud sounding turbo charger and causing high back pressure since the waste gate has been kept closed to deliver all that air that has been pumped out through the leak. Idle problem at hot engine indicates that there has been a leak. I had a similar problem before when an EGR gasket was missing. So, when I gradually raised rpm and load it came to a point where the cylinder pressure reached a high level while the exhaust back pressure escalated as well as the internal EGR level (hot residuals not scavenged), which all together caused severe knocking at the hottest point in the cylinders - between the exhaust valves on the squish plateau. Yes, the engine has a knocking sensor, but the ignition retardation strategy is probably a poor protection against such a massive local overheating at high load. The pressure amplitude from knocking can reach several hundred bars and is moreover amplified in between piston and cylinder.

I have two engine failures in my Lotus Evora S behind me, which were caused by high rpm knocking breaking the piston between first and second ring making the compression ring to collapse. All this was caused by a melted pre-cat that blocked the exhaust flow. The second failure was caused by the authorized workshop who replaced the engine and did not check the main cat, which were melted as well in the first failure

I do not think that something that radical has happened to my Q4 since the liners looks fine and there has been no mechanical rattling, but minor ring or piston damages could cause severe blow by which at high load create huge crankcase pressures. Then you have oil all over the place

So, lessons learned. Drive the car more often so that you know what it should sound like!

[#84]

.. and I probably don't have time to check more the coming three weeks since I have two cars that more urgently needs attention and on top of that I will be traveling for two weeks. So, to be continued in mid November

[Steve Webb]

Ok, I can see your train of thought there, but just to be clear:

1. Inlet runner rubber leaks.
2. Wastegate doesn't open, causing excessive pressure.
3. Excess pressure contributes to knock in cylinders.
4. Cylinder knock damages compression rings.
5. Damaged compression rings allow blow by in the cylinder, pressurising crank case.
6. Crankcase pressure blows oil out through oil vapour seperator.
7. Oil passes through compressor of turbo, finding its way into intercooler pipe.

Just a couple of things that trouble me with this.
First one is the Inlet rubbers, if you look at the pics that Jack posted earlier, very little of the rubber is exposed to inlet pressure, making it more difficult for a leak to develop.
Secondly, there are a number of one way valves in the vapour recovery system to prevent such a scenario as you are seeing. Also to have this problem in such a short space of time, I would have expected damage to the cylinder bores from a catastrophic compression ring failure.

All that said, a strip down of the vapour recovery system is pretty simple so the logical place to start really.

Whilst you are at it, I'd check all of the small bore hoses in the engine as well.

Good luck when you get some time to get your hands dirty again. And keep us updated.

Steve

[#84]

Thanks for your input - and yes you got me right. I will check the oil vapor recovery system with the excellent motivation that it is simple in relation to strip down the engine.

One comment to the logic train of thoughts; combustion pressure blow by will build back pressure to the turbo oil return through the crankcase, which is the same as blocking the return, which was one of the two reasons the turbo provider listed as a direct reason for the turbo to leak extensively to both compressor and turbine. Both have been oil filled, with the difference that the turbine housing vaporizes, spit out, or "coxes" the oil, while the compressor leads it to the lowest and coolest point in the system.

[Steve Webb]

The more I think about it, the more high crank pressure makes sense.
The high pressure would prevent any oil drain back to the crank, and would increase the amount of vapour heading into the vapour recovery system.
With nowhere to go the vapour would end up in the inlet and find itself at the lowest point- the intercooler inlet hose.
Let us all know what you find when it comes apart.

[#84]

.. finally. The engine is out. We made a good deal on a two pillar lift this spring, which makes life easier. However. An engine job on a Q4 is NEVER EVER easy.
What I know, so far:
- Nothing wrong with the oil vapor separator
- Nothing wrong with the turbo
- Camshafts aligned, not checked vs crankshaft just against each other
- Oil in intercooler, exhaust, air filter box, throttle body
- Greasy intake runners, oil on AC-compressor
- Massive leak rate in all cylinders - massive crankcase oil smell while testing
- Cylinder linsers and piston top looks fine from endoscope analysis, with exception from some knock marks on top land between the exhaust valves
- Oil in cylinder four piston bowl

I add some pictures to prove that something is actually happening after 9,5 years without regular use of the Q4!

[Steve Webb]

Glad to see things moving ahead for you.

Quick querstion that I've posted elsewhere, when you disconnected the oil temp sensor, where did the wire come from? Mine is no longer connected (probably when the garage replaced the alternator) and I can't find the wire to plug into the sensor now.

[#84]

Steve,

The cable is light grey, or white, with a red stripe. Picture 1. It goes together with the cable from the 2-pole contact with yellow sealing, seen in the forefront of the picture 2. They join in a woven rubber coated cable protector, circa 5 mm dia. See first thin green arrow in picture 3. They then join all the other sensor cables at the second thin green arrow in picture 3, to finally end up in the ribbed black plastic cable protector that runs below the coolant expansion tank with the blue plastic hose etc next to it, up along the right strut top mount. In picture three, the oil temp contact could be seen just on top of the big green X and the thick green line goes along the cable past all joints.

I hope that is of some help, otherwise we can sort it out live when I am in the workshop.

[Steve Webb]

Awesome, that clears things up brilliantly.

[#84]

Piston 1, 2 and 4 - all broken in ring land between 1st and 2nd, respectively 2nd and 3rd piston ring. Various degree of fracturing, but still cracked. Fortunately the cylinders are fine, no scratches. So are all the bearings, which were new.

The hypothesis is that all oil that has been found everywhere was pushed out by the combustion pressure when the pistons broke at full boost at 5000-5500 rpm. Then, at some minor acceleration, the oil that stood in for example the intercooler, was swept into the engine and caused smoke clouds.

To be continuoued.