Gordini Head Gasket and Investigation

[malcolm]

I got around to removing the cylinder head from the Gordini this afternoon. I hadn't got around to doing a compression check, but identified a problem with the distributor that might have explained some of the running problems.

Further issues were the bong bong noise at idle similar to this thread http://www.renault4.co.uk/forum/showthread.php?t=3527 and of course all the water that made it's way into the oil during the Kent run.

I'll go about the head gasket first. The bong bong noise is most likely the timing chain, but I don't want to tackle them both at the same time as I'll never be sure it definitely is the timing chain bonging, and I have another car in the yard making the same noise so would like to be completely sure.

Some pictures for now.

There's definitely some water in the oil. Nasty scum:


The head has been removed in the past - but not recently as the gasket has had time to go a bit nasty. Some discolouration there amongst other things.


Somebody seems to have honed the bores at some point. I hope they took precautions with the liner seals.


If anyone spots anything I haven't do shout. The last MOT for that engine was in 1999, but I have no history. The head does need a skim even judging from my not very straight edge, but the liner height looks good.

More later.

 

[Steve Hennessey]

Malcolm - they wouldn't have honed the bores in situ - a full strip down would be needed. Looks like the original marks are from when the engine was built, therefore showing little wear. When I did my head gasket at approx 90,000 miles there were 'honing' marks in my bores.

The two middle cylinders are a bit oily and I can see where there has been slight water leakage into the combustion chamber. I would have like to have seen a photo of the head minus the gasket.

How sure are you that the head has been removed before? There are usually tell-tale signs. Providing that there is no leak from the liner seals (which is impossible to test now) it looks like this is a routine top end overhaul job and proving all the rules are followed without any cost cutting, then this engine should last you many more smiles over the next few years!!

Your 'bong bong' noise is definitely the timing chain - if I'm wrong then I will supply you a few beers at the next Barbie!!

Please let me know what you found in the distributor?

Best of luck

Steve

 

[pepper]

I seem to remember you saying that the engine had been stripped before (hylomar everywhere) I hope that the head hasn't been skimmed too much otherwise it may prove difficult to keep compressions down as the non turbo engine has a pretty high ratio as standard IIRC.

The bolt holes in the head look like they have a lot of oil in them, did that get in there during the strip down or was that like that already? If so that would give false reading when torquing the head down!

 

[malcolm]

I had thought the honing was a sign of some rebuild work, so this might well be the first time the head has been off - the mileage is about 60,000 according to an old MOT.

I forgot to take a photo with the gasket removed from the head. There was similar discolouration to the other side. It's just a suspicion I have that the advance weights aren't working properly in the distributor - I'll check that before it goes back in.

Will be careful with any skim - I'm surprised they can get away with the standard compression ratio on those.

PS - for the bong bong noise I'm not ruling out combustion blowing into a nearby cylinder with a valve open and resonating in the intake manifold. I'll match your beer.

 

[pepper]

OOoo there's some mans talk going on here! I better get my coat and leave

 

[John Doe]

Few minutes ago I was checking oil on my Alpine engine and it's ok, but it seems that we have a similar problem, I too have some white "mayonnaise" on my oil filling cap.

 

[pepper]

John, they always get a little mayonnaise on the oil filler caps on these engines, it depends if its just on the cap or in the rest of the oil mix, have you checked the dip stick to see if that oil is mayonnaised too?

 

[John Doe]

The oil on the dip stick seems to be just fine.

 

[malcolm]

My dip stick was covered in froth. You might just have a little condensation left over from the rebuild, or if the head was off there's a good chance you will have a little water in the oil from that. Best to wipe it clean and keep an eye on it.

 

[John Doe]

Thank you, I will keep an eye on it

 

[Steve Hennessey]

I had thought the honing was a sign of some rebuild work, so this might well be the first time the head has been off - the mileage is about 60,000 according to an old MOT.

I forgot to take a photo with the gasket removed from the head. There was similar discolouration to the other side. It's just a suspicion I have that the advance weights aren't working properly in the distributor - I'll check that before it goes back in.

Will be careful with any skim - I'm surprised they can get away with the standard compression ratio on those.

PS - for the bong bong noise I'm not ruling out combustion blowing into a nearby cylinder with a valve open and resonating in the intake manifold. I'll match your beer.

If 60,000 is the correct mileage then that's good news - just barely run in!!

I will really look forward to my beer

 

[malcolm]

Now there is a beer at stake I'm planning to be extra careful with the rebuild.

Couldn't find a straight edge but I did unearth a surface table which still seems relatively flat. The head was 0.1mm high between the front two cylinders so I've dropped it in for a skim.



One thing that seemed slightly odd is number 3 exhaust valve looked a bit thin (to the right in the photo but you can't see much). The seats look clean, and while that seat was very slightly curved I couldn't see any evidence of that valve having lost any metal. The engine builders didn't seem bothered. Do you reckon it's worth a new valve?

 

[Steve Hennessey]

Hello Malcolm - please take some advice from an old mechanic.:idea: A good way of checking if the valves are seating is to pour a little bit of paraffin into each chamber - enough to cover the valves. If any of the paraffin leaks out then take all the valves out, check the valve seats and the valve inserts and if they don't look too bad then de-coke and grind the valves in, checking every so often with a small amount of engineers blue to ensure they are making a perfect seal.

If there's any doubt about the seats or the valves then get them refaced or replace. My method of working, especially on engines, is not to leave anything to chance. It will pay off in the end

 

[malcolm]

Definitely agreed with that. I tend to do a good clean up and give all the valves a light grind anyway while the head is off.

I'll find a new valve - It's a bit thin and I'm not sure why, but I don't want to pull the head off again so worth dealing with that now. I reckon the seat is good at the moment but have struggled to find consistent info about the seat material. Must remember to ask the engine rebuilding people if they have a hardness tester. For the amount of motorway miles I do it's best treating it like an 1108 (additive for the motorway).

 

[Steve Hennessey]

When I removed my R4 head I had the exhaust seats replaced with harder ones. However, it may be more economic for you to use Valvemaster or something similar as I assume you won't be doing many miles in a year. If you can get the seats tested for hardness then it may save you some money if they are ok. I just had my seats replaced as a precaution.

I'm sure that you won't leave and problem you find as pulling these heads off can be a pain.

I can already taste the beer in advance of you removing the timing cover

 

[Charliemouse]

While the head is off

If it were my engine, while the head is off:

Take it to a good engineering shop and get them to measure it for face flatness. If it more than .0002" (2 thou) out have it skimmed. The minimum they will be able to take off is around .0010". My Engineering shop will drive to me to check the block face with the engine in to save us having to take it out. If you can find a good straight edge, a cigarette paper is 2 thou - and this is again the max allowable in most cases. Make sure the liners havent moved. You can have the Engineering shop do a leak down test - they should have better techniques than parafin these days! If it were me I'd have inserts put in and new valves to suit (they should be able to find you some if they do heads a lot).

Your table top is not flat enough to detect .1mm!

The usual cause of head gasket failures in liner engines is over-heating - general or local. Make sure all waterways are clear and routing - even of heater hoses, is as standard. Thermostart should usualy be in - taking out can disrup flow locally. Second cause (old engines mainly) is no inhibtor in the coolant allowing reaction/electolosis and the gasket being eroded. The next on the list is the head bolts. Are they stretch bolts on this engine? If so measure tham as they go in (to nearest thou) and fit NEW. If you do have to take it down if they have not stretched they did not pass their elastic limit and will go again. If they are ANY longer - they go in the bin - and you ask why! (wrong torque, bad assembly sequence, block flex, major heat etc).

In summary - do it once, do it right - never do it again.

I have a good shop who just charged me £50 for skimming the head and calling over to check the block on a £20k Turbo Duratec engine in my Hillclimb car, and £120 for new seats on a Kent (I provdided the valves).

Regards

Charliemouse

 

[malcolm]

Thanks - that's very good advice. Well worth checking and sorting everything possible while the engine is in bits. My solutions might be a little more economical but that's only because I don't have a spare £200 just now. But I'll certainly sort out bits that are wrong.

Head is in for a skim. It was a proper surface table - they are ground to very flat though mine is a bit knackered so I measured in a few different spots on the table.

I'm not sure how to check the liner seals - I always worry about them, though as Steve mentions the engine will likely have to come out to sort a timing chain issue so I'll have a chance to check everything else is working when the head is back on. Figured the only painful thing I will have to do twice would be to disconnect the exhaust.

Would love to see pictures of the hill climb car.

 

[Steve Hennessey]

There's one way to check the liner seals but the engine has to be together and filled up with water. You can buy, beg, borrow or steal a cooling system pressure tester http://autotrader.edirectory.co.uk/...ing+system+pressure+tester+sykes/pid/9103255/

I had one of these years ago and they work really well. There is an adapter to fit onto the radiator and pump it up to around 16lbs per square inch and if the liner seals have deteriorated then water will come out of the sump plug!!

I remember using these in 1968 when I was an apprentice and have never forgotten how accurate they are.

 

[pepper]

Or it wouldn't take many minutes to make your own with a few spare bits taken from other Renaults, a pressure gauge, and an airline.

Bodgity is the bestest way!

 

[malcolm]

I had hoped to cut in a spare valve from a seized spare engine as the rest didn't seem too bad, but it turns out the seized engine may have been stored outside for some time in the past and is chock full of corrosion.

The engine re-builder has quoted around £240 for unleaded inserts and grinding in new exhaust valves, but they can't source valves. Neither can Renault.

Derek (Renospeed) has a spare used one sitting on his desk which should open up the botch option again. Could always go for a new seat in that one. Can anyone think of where to source 4 new exhaust valves?