1.8t hgf

[kaiser]

This is a repeat from another thread:

I hate to admit it, but my 1.8T is going again. It has just done 15000km since the last head gasket repair, and I did it myself, as well as it can be done.

The car has gradually started to use water, and now it is pressurising the coolant system and a pipe has blown.
Three of the spark plugs show signs of water, and there is no doubt in my mind, the gasket is going. No other symptoms and no oil/water mix. Just high pressure and water in the cylinder(s) and general water loss.

I recently tried to re-torque the engine bolts, to see if I could maybe save the day, and first slackened them of in sequence. I made a note of the torque required to "break" each bolt, and that varied from 25 to 40 Nm. It had no effect, at least not positive.

And a similar story. A couple of years ago, I had head gasket failure on a 7MGE Toyota Cressida engine. I bought new gaskets and had the head skimmed and valves sorted. Fitted the head and read up about the torque. From memory it stated that the recommended torque was 70Nm, but there is general agreement that that figure is too low, so I gave it 90Nm.
All was well for about 5000km, and it went again. I took the head in to be skimmed again, and spoke to the owner of the business, he asked if I had re-torqued the head, and I said no, but I had given it extra torque. He went into the computer and came back and said the head had to be re-torqued after the first 800km. I fitted the head, torqued to 90 again and drove about 1000km. Then I re torqued all bolts again, and the most telling aspect is, that when "breaking" the bolts, they all were about 40Nm, that is less than half the original torque. So a settling of the gasket, and all sorts of heat and cooling effects, had brought the permanent torque to less than half of the original torque.
I have now driven that engine a great distance and all is well.

I am just quietly wondering if we are under torquing these k-4 engines? and further, if we would maybe not gain from re-torquing the head after say 1000km?

I know these are stretch bolts and all that jazz, but 3 spark plugs showing signs of water sounds like either a general lack of torque, or sunken liners on three cylinders.

And, I sealed the liners with Loc-Tite when installing them, so time will tell.

Time to take the head off.

The head has now come off, and it is clear that water has come past the fir rings especially on the two middle cylinders, on the pictures towards the bottom of the screen.

Any idea why?

I have written to Victor Reinz for their opinion, as I would really like to avoid a repeat!.All liners are proud, the head was skimmed and flat, new bolts, correct torque and procedure. No subsequent overheat, no mixing water and oil, only water in the cylinders and pressure in the cooling system.

[Lovel]

Originally Posted by kaiser

This is a repeat from another thread:

I hate to admit it, but my 1.8T is going again. It has just done 15000km since the last head gasket repair, and I did it myself, as well as it can be done.

The car has gradually started to use water, and now it is pressurising the coolant system and a pipe has blown.
Three of the spark plugs show signs of water, and there is no doubt in my mind, the gasket is going. No other symptoms and no oil/water mix. Just high pressure and water in the cylinder(s) and general water loss.

I recently tried to re-torque the engine bolts, to see if I could maybe save the day, and first slackened them of in sequence. I made a note of the torque required to "break" each bolt, and that varied from 25 to 40 Nm. It had no effect, at least not positive.

And a similar story. A couple of years ago, I had head gasket failure on a 7MGE Toyota Cressida engine. I bought new gaskets and had the head skimmed and valves sorted. Fitted the head and read up about the torque. From memory it stated that the recommended torque was 70Nm, but there is general agreement that that figure is too low, so I gave it 90Nm.
All was well for about 5000km, and it went again. I took the head in to be skimmed again, and spoke to the owner of the business, he asked if I had re-torqued the head, and I said no, but I had given it extra torque. He went into the computer and came back and said the head had to be re-torqued after the first 800km. I fitted the head, torqued to 90 again and drove about 1000km. Then I re torqued all bolts again, and the most telling aspect is, that when "breaking" the bolts, they all were about 40Nm, that is less than half the original torque. So a settling of the gasket, and all sorts of heat and cooling effects, had brought the permanent torque to less than half of the original torque.
I have now driven that engine a great distance and all is well.

I am just quietly wondering if we are under torquing these k-4 engines? and further, if we would maybe not gain from re-torquing the head after say 1000km?

I know these are stretch bolts and all that jazz, but 3 spark plugs showing signs of water sounds like either a general lack of torque, or sunken liners on three cylinders.

And, I sealed the liners with Loc-Tite when installing them, so time will tell.

Time to take the head off.

The head has now come off, and it is clear that water has come past the fir rings especially on the two middle cylinders, on the pictures towards the bottom of the screen.

Any idea why?

I have written to Victor Reinz for their opinion, as I would really like to avoid a repeat!.All liners are proud, the head was skimmed and flat, new bolts, correct torque and procedure. No subsequent overheat, no mixing water and oil, only water in the cylinders and pressure in the cooling system.

Yuk, what coolant are you running on, perhaps some errosion/corrosion of the firing rings ? I think the Rienz gasket is also to be fitted with 10.9ish stretch bolts and not the standard stretch bolts? With 10.9 you reduce the final torque angle, however perhaps you could use the normal 20nm, 180deg, 180deg to provide higher clamping force

If as you say the liners all have stick up and fall within tolerance then it is difficult to say really what the issue is.

How about this one, if you are non too fussed about taking it off again soon and as an experimment. Remove the folded steel shims on each end of the gasket. I would like to try this but have no test mule suitable for the moment. This would have an effect of reducing the surface area of the steel gasket and place a more focussed load on the gasket firing rings themselves, perhaps leading to indentation of the liners on the head, but so what, this engine design is so easy and economic to work on it is irrelevant in this case.

[beinet1]

Hi Kaizer,

Sorry to hear this, as I know you do your things thoroughly and correctly. What is the state of the cylinder head after dismantling? Any indentation or surface porosity?

Seems that this is another typical case of a perfectly fitted MLS gasket which fails for no reason. I am of the belief that this kind of gasket is not suitable to this engine as the design does not allow for sufficient clamping force needed to maintain the seal integrity of the MLS design.

Do you consider to go the SLS (elastomer) way?

This one has now covered 32000km without problems: http://www.the75andztclub.co.uk/foru...0&postcount=74

[Lovel]

Originally Posted by beinet1

that this is another typical case of a perfectly fitted MLS gasket which fails for no reason. I am of the belief that this kind of gasket is not suitable to this engine as the design does not allow for sufficient clamping force needed to maintain the seal integrity of the MLS design.

Do you consider to go the SLS (elastomer) way?

]

I thought it was the elastomer version initially. But MLS after second look. Perhaps he could also consider new one piece MG NAC type with high tensile bolts? Perhaps next best step is elastomer design with the relatively small cost compared to the NAC version

[beinet1]

Originally Posted by Lovel

I thought it was the elastomer version initially. But MLS after second look. Perhaps he could also consider new one piece MG NAC type with high tensile bolts? Perhaps next best step is elastomer design with the relatively small cost compared to the NAC version

To see some long term experience with the NAC gasket would be pretty interesting. I think that is a better way to go than the conventional MLS.

[RodgerD]

I've got two 1.8 turbo with HG problems and still to decide which gasket to use. I'm going down the route of sourcing 1.4 blocks as they shouldn't have been stressed like a 1.8T engine. I'm going to make sure liner protrusion is 0.005" and siding with the elastomer gasket, possibly with blue Hylomar. Going to look at torque settings, going to test an old oil rail to decide what torque the ladder threads will take and make a judgement.

I'm also looking at keeping the coolant as close to the thermostat temperature as possible and not rise to 100+ degrees before the fan kicks in. By the time the fan cuts in head temperatures will be well above 100 degrees C. Higher coolant temperatures compared with ambient temperatures means the coolant system is less efficient at dissipating the heat around the head, so every degree nearer thermostat opening temperatures means the cooling system is more efficient. Given the low level of coolant in the system, a close control of coolant temperature at around thermostat temperature should help with the head softening.

I'm also looking at under bonnet temperatures, as this will play a part as some of the heat dissipation is from the head external surface with the under bonnet enclosure creates a heat trap. One possible way of reducing under bonnet temperatures is to remove the centre section of the double bulkhead and allowing a heat flow route out through the driver's side scuttle vent, or modifying the centre section with extra vents. It might even be worth looking at installing fans where the bulkhead panel is now to give positive under bonnet ventilation.

If the k series HG issue is going to be solved, it requires looking at not just the engine with the problem of expansion of dissimilar metals, but its installation as well.

[bl52krz]

Originally Posted by kaiser

This is a repeat from another thread:

I hate to admit it, but my 1.8T is going again. It has just done 15000km since the last head gasket repair, and I did it myself, as well as it can be done.

The car has gradually started to use water, and now it is pressurising the coolant system and a pipe has blown.
Three of the spark plugs show signs of water, and there is no doubt in my mind, the gasket is going. No other symptoms and no oil/water mix. Just high pressure and water in the cylinder(s) and general water loss.

I recently tried to re-torque the engine bolts, to see if I could maybe save the day, and first slackened them of in sequence. I made a note of the torque required to "break" each bolt, and that varied from 25 to 40 Nm. It had no effect, at least not positive.

And a similar story. A couple of years ago, I had head gasket failure on a 7MGE Toyota Cressida engine. I bought new gaskets and had the head skimmed and valves sorted. Fitted the head and read up about the torque. From memory it stated that the recommended torque was 70Nm, but there is general agreement that that figure is too low, so I gave it 90Nm.
All was well for about 5000km, and it went again. I took the head in to be skimmed again, and spoke to the owner of the business, he asked if I had re-torqued the head, and I said no, but I had given it extra torque. He went into the computer and came back and said the head had to be re-torqued after the first 800km. I fitted the head, torqued to 90 again and drove about 1000km. Then I re torqued all bolts again, and the most telling aspect is, that when "breaking" the bolts, they all were about 40Nm, that is less than half the original torque. So a settling of the gasket, and all sorts of heat and cooling effects, had brought the permanent torque to less than half of the original torque.
I have now driven that engine a great distance and all is well.

I am just quietly wondering if we are under torquing these k-4 engines? and further, if we would maybe not gain from re-torquing the head after say 1000km?

I know these are stretch bolts and all that jazz, but 3 spark plugs showing signs of water sounds like either a general lack of torque, or sunken liners on three cylinders.

And, I sealed the liners with Loc-Tite when installing them, so time will tell.

Time to take the head off.

The head has now come off, and it is clear that water has come past the fir rings especially on the two middle cylinders, on the pictures towards the bottom of the screen.

Any idea why?

I have written to Victor Reinz for their opinion, as I would really like to avoid a repeat!.All liners are proud, the head was skimmed and flat, new bolts, correct torque and procedure. No subsequent overheat, no mixing water and oil, only water in the cylinders and pressure in the cooling system.

Hi Kaiser. Every engine I have ever changed the head gasket on, and every car I have ever bought, I have always re-torqued the head bolts. I know the bolts are special"stretch" bolts in the kv6 and 1.8, but if I ever bought one, that is one of the first things I would do. Right or wrong.