6.9 Intake Manifold

[TJ 450]

Hi,

As part of an engine revamp, I've had to remove the intake manifold.
I reinstalled the manifold last week, ran the engine, only to find some coolant leaks from the coolant ports into the cylinder heads.[V]

This afternoon, I managed to fully remove the intake manifold from the car, again. On the LH bank, where the two coolant leaks were, I have noted that the gasket has been compressed at the top, but the lower area remains only slightly compressed. Problem areas have been marked in the images.
See below:

Image 1
Image 2

The overall situation:
Image 3
Image 4

The other issue is the EGR pipe. It is a constant PITA and I still have not worked out how to remove/install the manifold without interferance. Surely there is a way around this? So far I have only been able to get it to clear by chance.

Tim

 

[Styria]

Hi TJ450, the way I see it, you must have a "physical fit" issue in some area. I am quite confident in stating that your problem is not one of uneveness in the two mating surfaces. Unfortunately, you'll have to start all over again, and that should include the purchase of new gaskets.

I would then also have a thorough check to make sure that the two manifold halves have been PROPERLY fitted and pushed together - check the eight connecting seals to make sure they're serviceable. I hope you bought new ones if you had the two halves apart.

The EGR pipe should present no problem, but just make sure that there is no physical interference when you re-install the Inlet manifold.

Other than that, I can only suggest that you use a very good quality sealant that you should coat the gasket with on both sides and both surfaces. Please keep us posted as to how you get one. Regards Styria

 

[BAR]

There is always the possibility that your head has 'warped', which could give rise to the uneven fit [hence differences in compression of the gasket] and also the leaking of coolant.

Whilst you have done m,ost of the effort and will have to buy new gaskets and head bolts to fit it back on, spend a few hundred more and get the head 'refinished' or planned to ensure that its surface is flat and smooth.

ALso be very careful to ensure the block has been cleaned thouroughly to ensure a clean surface for the new gasget.

 

[TJ 450]

Thanks for the replies.

The pics you see are as it is now. I am indeed starting over.
The eight connecting pieces are all new, everything has been cleaned and the two halves are properly secured.

It has been suggested that I loosen the EGR pipe stay and connection, although I don't see how the latter is possible as it seems you can't access the lower clamp on the throttle housing boot when the unit is installed to retighten it. The pipe causes interferance when fitting, damaging the surface of the gasket in the process.

I haven't removed the cylinder heads and I wasn't planning to, although I'm starting to think otherwise, as I'm missing the 13mm spacer tube on the LHS head bolt.

Tim

 

[Styria]

Just not quite sure what more I can suggest. Again, I very much doubt that there is a head/inlet manifold warp issue. I take your point as far as previous head removal is concerned, but it still looks an unlikely source to your problem.

I do recall, Tim, that there appeared to be some anomaly as far as head bolts were concerned - you know I just can't quite recall the exact 'puzzle' - it seemed to relate to one of the bolts seeming to be too long, but it got sorted in the end by careful observation and 'trial-fits' - again, sorry I cannot recall better.

It seems to me to be quite drastic to remove the head(s) unless you want to carry out further work. It is not easy, certainly time consuming and does cost money.

Seeing that the Inlet manifold is removed, I would carry out a trial fitting without the EGR pipe in place, and also make sure there are no other parts that may prevent a flat fit - once in position, just 'rock' the manifold to determine that there is no interference. THat's about all I can suggest at this stage. Regards Styria

BTW - did you receive the reconditioned bottom ball joint for the rear strut ? I hope it has arrived safely.

 

[TJ 450]

I'll give that a go, Styria. When the work was being done on your GB, were there any clearance issues with the manifold when installing/removing?

I won't be touching the heads other than ensuring that the surface is flat and clean.

Regarding that strut balljoint, it arrived at the PO on the 21st although when I went to collect, they couldn't find it. It has been confirmed that it is actually there, so I'll be going in there tomorrow.

Tim

 

[Styria]

Hi Tim - wise move. Why spend money needlessly, and time, when there is no need for it. Just as a matter of interest, have you ever taken a compression reading of the cylinders ? Sometimes, 6.9's can be prone to have low compression, usually on two cylinders - but NOT alongside each other.

When I refitted the Inlet Manifold, there were no clearance issues, including the EGR pipe. I did use a good quantity of the red Loctite gasket sealant, and I have had no problems - certainly not so far. As I said, carry out a trial fit (without gaskets) and just have a 'feel' of the fit.

From another post re Balljoint, I can't open the picture, but I am glad that it has arrived safely. Regards Styria

 

[TJ 450]

I performed a compression test earlier and found all to be within 5%, from memory, so there's nothing wrong with compression.

I checked the cylinder head surfaces with a straight edge this afternoon and found it to be acceptably flat, I'm about to check the manifold now and then I will fit it without the EGR pipe and check clearances.

Tim

 

[B13]

Do we even need the EGR? I mean, it neither increases nor decreases performance, it just feeds the engine some of its own exhaust to keep the oxides of nitrogen in the exhaust down.

The oxides of nitrogen are high due to the afterburner air-pump exhaust emissions control system.

I can only speak for rotary engine cars, but one of the things we do to them to simplify the external aspect of the engine is ditch the air pump, coasting and decel control valves, EGR system, and only leave in place the crankcase ventilation system. Emissions go up a bit, but economy gets a bit better, but other than that there's no real side effects.

Is there any reason we can't apply the same theories to MB engines?

I.

R/R 0%

 

[TJ 450]

I have heard that the EGR system also lowers combustion temperatures lessening the chance of ping occuring. Removing all pollution controls will increase economy at the expense of emissions, as you have stated, Ian.
However, I must leave all emissions gear intact as my car will need to be inspected for rego shortly. In this state it can only be done by the Department of Transport etc, etc.

The manifold fits perfectly without the EGR pipe attached, in fact it just drops straight in.

One thing I did forget about was that I used some dabs of blue hylomar to hold the gaskets in place. I think it may have interfered with the gasket's sealing properties in those areas and combined with a lack of torque on some bolts, caused the leak.

Tim

 

[Styria]

Well Tim, that's a bit more like it, isn't it ? If I were you, I'd just straight get on with it and refit the manifold. As previously mentioned, you may wish to use the red Loctite gasket maker - Hylomar might be okay as well, but I have only ever used it for head gaskets and thus I am unable to offer any constructive comments if you were to use it for manifold work.

Couldn't help but notice the excellent detailing and work you have carried out in the engine bay - it is quite satisfying, even for me, to witness the standard you have achieved. Ditto with the strut - very neat ! Regards Styria

 

[TJ 450]

It certainly is, Styria. I'm slightly hesitant to use the anaerobic sealant, just because it wasn't there originally, although I think I will.
I won't be able to fit it just yet, as I'm awaiting a full set of bolts, washers and the gaskets to arrive from Germany.
Thanks for the compliments, I've certainly spent a lot of time getting this car towards a level I'm satisfied with and I still have a fair way to go. I've not been one to like the existance of unknowns.
I also continue to be amazed by the lack of rust in this car, who would have thought, considering the condition I found it in?

Tim

 

[WGB]

I also continue to be amazed by the lack of rust in this car, who would have thought, considering the condition I found it in?

Tim

You will have to make the decision some of us have made about driving it in the rain or at least make sure it is completely leak free.

Bill

 

[Styria]

Hi Tim, not sure how right you are but, as I have previously said, start all over again. This is a pretty simple and straight forward job, and I really cannot see any reason why it should not remain so. Unless, of course, youhave 'goofed' somewhere along the line - easy to do. Regards Styria

 

[TJ 450]

There's not a chance this car is going to be driven in the rain, or for utilitarian tasks. Once registered, it will be stored at my off-site storage facility, fully enclosed and out of the weather. The 450 will take the place of the 6.9 under the carport.

I believe I "goofed" on the torque of the bolts, hence the leak. The decision is final, I'm using Red Loctite on a fresh set of gaskets with a full new set of genuine bolts and washers.

Tim

 

[Styria]

There is just something that's come to mind after I read your last post. You say that you have ordered gaskets and bolts from Germany - right ? Let me tell you my experience with the supply of replacement bolts from MB in Melbourne - ordered through one of the local Sydney dealers.

You will not get the original bolts with the 'plain shank and thread' - chances are that the bolts will be 'threaded' all the way. As far as I could see, their quality seemed to be almost 'GO LOW after market' - at least as far as I could tell and they were not cheap - I finished up, at that time, buying 'locally' hi-tensile units from a nut and bolt supplier in Sydney. I'll be interested to see what you finish up with. Regards Styria

 

[TJ 450]

Yes, my experience with genuine fasteners has not been overwhelmingly great so far, either. In this case they weren't particularly expensive and they should be correct according to MB part nr. supersessions.
It remains to be seen and I'll be collecting the parts from the dealer on Saturday morning, if all goes to plan.

Tim