KV6 HGF...worth repairing??

[paulh260260]

Originally Posted by SD1too

By "heat exchanger" T-Cut is referring to the oil cooler Paul, not the radiator. If the oil cooler was mixing oil and coolant I would expect you to have serious mayonnaise in the expansion tank. Have you?

If I were you I wouldn't ignore T-Cut's very interesting and informative crackle test. I'd like to hear the result of that.

Simon

Hi Simon

Update on a few things

1. Crackle test

The oil immediately starts to smoke as it heated up then there is definite and clear crackling as the water boils off.

2 Pressure test (sort of)

Opened the header tank cap after a night stood still and there was clear whoosh of pressure being released.

3. Presence of gas in header?

I've managed to get hold of a block tester but cannot use it as the level in the header tank rises within 30-40 seconds of engine being switched on from cold. As I've bled it properly why is this happening and where is it coming from.

4 Engine Temperature

Tried a short drive of 2 miles, stop start, with heater full blast red hot in the cabin, I even switched off at notoriously long wait light. On my return the temp had hit 105 degrees.

5. Hose Temperatures

Checked the hoses on my return and the top hose still hot but the bottom hoses was warm from the thermos to beyond the bleed screw ( as far as I was prepared to reach into a hot engine!!).
The bottom of the bottom hose, the part connected to the Rad was stone cold , as was the bottom of the rad.

So some new information there, any comments

Cheers

Paul

[T-Cut]

Hello Paul,
Thanks for your feedback on your investigations. I fear it looks like there's at least a failure in the oil cooler. Unfortunately, that in itself can't explain all your symptoms.

Originally Posted by paulh260260

1. Crackle test
The oil immediately starts to smoke as it heated up then there is definite and clear crackling as the water boils off.

The oil is emulsified with coolant. Likely cross-contamination via the oil cooler.

2 Pressure test (sort of)
Opened the header tank cap after a night stood still and there was clear whoosh of pressure being released.

The only feasible explanation of excess cold pressure is from exhaust gas pumped into the cooling system. Hot oil entering the cooling system via the oil cooler wouldn't create a persistant cold pressure.

. Presence of gas in header?
I've managed to get hold of a block tester but cannot use it as the level in the header tank rises within 30-40 seconds of engine being switched on from cold. As I've bled it properly why is this happening and where is it coming from.

Could be very hot oil entering the system via the oil cooler or exhaust gas pumping in via a gasket fissure, cylinder crack, ?.

4 Engine Temperature
Tried a short drive of 2 miles, stop start, with heater full blast red hot in the cabin, I even switched off at notoriously long wait light. On my return the temp had hit 105 degrees.

Engine is overheating. Did the radiator fan operate? If so, did it reduce the temperature to below 100C?

5. Hose Temperatures
Checked the hoses on my return and the top hose still hot but the bottom hoses was warm from the thermos to beyond the bleed screw ( as far as I was prepared to reach into a hot engine!!). The bottom of the bottom hose, the part connected to the Rad was stone cold , as was the bottom of the rad.

Another sign that the coolant isn't circulation through the radiator, possibly due to a suspected fault around the oil cooler.

TC

[paulh260260]

Originally Posted by T-Cut

Hello Paul,
Thanks for your feedback on your investigations. I fear it looks like there's at least a failure in the oil cooler. Unfortunately, that in itself can't explain all your symptoms.

The oil is emulsified with coolant. Likely cross-contamination via the oil cooler.

The only feasible explanation of excess cold pressure is from exhaust gas pumped into the cooling system. Hot oil entering the cooling system via the oil cooler wouldn't create a persistant cold pressure.

Could be very hot oil entering the system via the oil cooler or exhaust gas pumping in via a gasket fissure, cylinder crack, ?.

Engine is overheating. Did the radiator fan operate? If so, did it reduce the temperature to below 100C?

Another sign that the coolant isn't circulation through the radiator, possibly due to a suspected fault around the oil cooler.

TC

Cheers TC

Sounds like a whole host of problems, the oil cooler and thermos whilst costly to repair, are at least solvable. However its becoming more likely that there is a more serious problem with the engine.

Paul

[SD1too]

Paul; thanks very much for your detailed test results. I have a slightly different opinion to T-Cut's.

Originally Posted by paulh260260

1. Crackle test
The oil immediately starts to smoke as it heated up then there is definite and clear crackling as the water boils off.

T-Cut says that this indicates that there's water in the sump. So you have emulsified oil there and in the cylinder heads but not in the cooling system.

Originally Posted by paulh260260

2 Pressure test (sort of)
Opened the header tank cap after a night stood still and there was clear whoosh of pressure being released.

If it's a substantial release of pressure then that strongly suggests pressurisation via a blown cylinder head gasket.

Originally Posted by paulh260260

3. Presence of gas in header?
I've managed to get hold of a block tester but cannot use it as the level in the header tank rises within 30-40 seconds of engine being switched on from cold. As I've bled it properly why is this happening and where is it coming from.

The rise in level in the expansion tank is likely to be due to combustion gas entering the cooling system via a blown cylinder head gasket.

Originally Posted by paulh260260

4 Engine Temperature
Tried a short drive of 2 miles, stop start, with heater full blast red hot in the cabin, I even switched off at notoriously long wait light. On my return the temp had hit 105 degrees.

Overheating is often, but apparently not always, a sign of a blown cylinder head gasket.

Originally Posted by paulh260260

5. Hose Temperatures
Checked the hoses on my return and the top hose still hot but the bottom hoses was warm from the thermos to beyond the bleed screw ( as far as I was prepared to reach into a hot engine!!).
The bottom of the bottom hose, the part connected to the Rad was stone cold , as was the bottom of the rad.

This is a cooling system issue not related to the mixing of engine oil and coolant. It's an odd set of test results and may well correct itself when the main problem is solved.

Paul; I don't routinely shout "head gasket failure" from the rooftops but the evidence you've provided makes me strongly suspect it. If the oil cooler fails, engine oil is injected into the coolant on its journey back to the engine. The entire cooling system becomes contaminated but you don't have that symptom, so my money is on the gaskets. It's going to be an expensive repair but at least you'll get a cambelt change virtually free of charge. I know, not much consolation.

Simon

[Lear]

I think you need to make a decision. It appears you are trying to harness support to convince yourself that the head gasket has not blown. I think the symptoms are BHG.
One way is to stick some K sealant in and see if it cures it, or at least makes it better/driveable/cooler. That way you will at least have an answer. I know it is a bodge but at least it will put us all out of our misery wondering.

[paulh260260]

Thanks for all your advice Simon, much appreciated ( The same goes to Tcut also ).

At least we've done as much as possible to eliminate everything we could before coming to the dreaded head gasket failure conclusion.

Incidentally once I added Wynn the engine sounded much better but removing it and refilling with semi synthetic 10/40 has made it almost go back to the same sound.

It's difficult to describe other than metal to metal knocking from the front bank. Normally I would have dismissed it as maybe piston slap but with the garage saying it sounds like a warped engine they don't want to touch it, so I can't even get it repaired locally.

Paul

[stocktake]

Lets go back to post 5 on this 67 post long thread. It won't cost the earth, and it should provide you with some answers good or bad.
"bypass the oil cooler"
I would follow this up or precede this with a compression test. Again doesn't cost a fortune and will give some answers.

One would prove/disprove Oil cooler failure
The other would prove/disprove HGF

All for the price of a bottle of stealseal.....

[paulh260260]

Originally Posted by stocktake

Lets go back to post 5 on this 67 post long thread. It won't cost the earth, and it should provide you with some answers good or bad.
"bypass the oil cooler"
I would follow this up or precede this with a compression test. Again doesn't cost a fortune and will give some answers.

One would prove/disprove Oil cooler failure
The other would prove/disprove HGF

All for the price of a bottle of stealseal.....

Yep Dave I think we've concluded its the HGF but you're right I need to bypass the oil cooler to prove or disprove a blockage causing lack of flow around the rad, after all no point in lobbing in steel seal if its already blocked.

Paul

[Lear]

Hi Paul,
Are you a half competent DIY mechanic? If so do the head yourself. A couple of weeks ago I thought I was going to have to do one on my KV6. I have only just bought my ZT-T from a guy who was giving it away because the garage had diagnosed a dropped valve and wanted £1,500. I bought the Haynes manual and read and re-read the section on cylinder head removal about 10 times. Not difficult, tricky maybe but simple enough if you are methodical and have the special tools. Including a head skim and belts I reckon you would spend £400-£500.
Anyway, before I started I plugged in my OBD tester and it showed no.4 cylinder misfire. Yes a £14 coil pack!, Running beautifully now but a bit disappointed I did not strip the engine. F......g garages.
IMO it is always worth spending money on an old car provided you like the car and want to keep it. Buying a newer second hand car does not guarantee lower bills. Better the devil you know.
There must be some like minded people near you who can help. If not we are here to talk you through it. First stop is to buy the Haynes if you have not already got it.
Happy spannering.
Simon

[Ducati750cc]

If there are combustion gasses entering the cooling system they will show up with a good quality gas tester.

Failing that a thorough cooling system pressure test as I mentioned previously, plus, as Stocktake mentions a compression test.

One other not often mentioned or used is a cylinder leak tester, or leak down tester.

Basically it has two pressure gauges on a tube, one end has a connection to a compressor, the other end has an adaptor to screw into plug holes, between the gauges in the tube is a calibrated restricted orifice.

The first gauge measures input pressure which you usually set at 100 Psi. the second measures the leakage as a percentage.

It can be a bit of a rigmarole the more cylinders there are but can provide so much information.

Briefly, take a 4cyl engine, remove all the plugs, get No 1 to TDC both valves closed, put the car in gear to prevent the engine turning fit the adaptor into No 1 plug hole, then turn on the air and set the input gauge at 100 Psi, observe and note the reading on the leakage gauge, there will be some leakage, also fill the radiator or expansion bottle to overflowing, remove the dipstick and oil filler cap and remove the air filter to carb, throttle body pipe, then whilst all is still connected and under pressure, listen at the following for the sound of air leaking, sometimes easier with a stethoscope or piece of tube.


A) Exhaust pipe, signs of a burnt valve or no valve clearance, or other valve / seat problems.

B) Carb, throttle body inlet, as above, valve / seating problem etc as with the exhaust.

C) Oil filler cap and, or dipstick tube, possible ring damage or ring bore wear/ damage.

D) Radiator filler neck or expansion bottle neck, visible bubbles, or if not filled to overflowing sound of escaping air in the expansion bottle or radiator, signs of head gasket failure or cracked liner or cracked head in some instances.

E) The plug hole of the adjacent cylinder, or cylinders to that being tested, shows head gasket, cracked head problems between cylinders.

Obviously as each cylinder is tested, it must be brought to TDC with both/all valves closed and the above repeated, a healthy engine will show all cylinders leak a small amount and about equal and this will be past the piston rings, any with a greater leak points to that cylinder only.

It can show single areas needing attention as above or multiple areas.

If you get time Google a video of it, a video will explain far more than my brief description here.

Stocktake also mentioned Steel Seal, though not the cheapest sealer, it is about the best according to my son, though not intended be to a permanent repair, as long as the instructions are followed to the letter, he has been surprised in many instances how well it has worked and how long it has lasted on customers cars who have been skint, just wanted the car to last another couple of months, or to save up for the proper job to be done and having stripped them down for the proper job at a later date has been able to see how effective it has been, but it won't always work on substantial problems.

The testers are quite reasonable and you can make one, as I did aeons ago for two reasons, one I'm tight, two I'm always of the mindset of " I bet I could make one " the photo is of my Blue Peter, Heath Robinson one, after a bit of rooting in my ' that may come in handy, cabinets, drawers and cupboards' and it's as accurate but not as posh as my sons.


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