Another rebuild already??

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Another rebuild already??

Postby LewisMac » 09 Feb 2020, 16:25

2.1 DJ 1988

Hi guys.

In the past year I’ve had a full rebuild including,

2 new heads
Thermostat
Radiator
Various coolant pipes

And some other stuff not related to cooling system.


Symptoms are,

1.Header tank keeps emptying into overflow tank. (I get the flashing red light 20 mins into a journey)

2.Header tank won’t suck back in any coolant.(I have 2 dalek caps from brickwerks)

3. When I open the header tank cap I get a hiss and coolant rises slightly. (Cold engine)

4. When I bleed the coolant system.
I start her up, unscrew the blue cap, and before I go to top her up I watch the coolant level rise up and out of the tank. ( on tickover without raving the engine)


Sounds to me like exhaust gas getting into coolant system...fire rings?

Both heads have no trace of coolant leak, no pink stains anywhere I can see.


This van has had 3 rebuilds in the past 5years.

1st one by VW before I got her.(reconditioned engine)

2nd one because of I used a dodgy mechanic who cost me a cylinder head.

3rd time June last year, apparently because the previous mechanics poor rebuild job causing the other head to go.

I’ve no idea where to go from here.
Is there any point in attempting another rebuild.

Thanks in advance for any help.














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Last edited by LewisMac on 11 Feb 2020, 11:54, edited 1 time in total.
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Re: Another rebuild already??

Postby lefty67 » 10 Feb 2020, 09:15

Exact same symptoms as mine. After alot of chasing around including new thermostat, pump, coolant changes etc. It turned out to be a cracked cylinder head!
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Re: Another rebuild already??

Postby silverbullet » 10 Feb 2020, 10:27

Any "rebuild" that doesnt go right down to the crankshaft and cam replacement...isn't a rebuild.

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Re: Another rebuild already??

Postby LewisMac » 10 Feb 2020, 14:34

lefty67 wrote:Exact same symptoms as mine. After alot of chasing around including new thermostat, pump, coolant changes etc. It turned out to be a cracked cylinder head!


Any idea why the cylinder heads are cracking?

I’ve got 2 brand new heads on there.


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Re: Another rebuild already??

Postby lefty67 » 10 Feb 2020, 15:02

Mine, only one on a diesel, I suspect, was due to overheating. I am sure my mot guy left it running on its test and the fan never kicked in.
Ran it for about a year with the problem, sometimes it was ok sometimes pressurising, eventually it was pressurising all the time.

Yours, if not overheated, could be due to poor quality heads maybe or incorrect thickness head gasket. What metal are the heads made from?
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Re: Another rebuild already??

Postby LewisMac » 10 Feb 2020, 15:30

lefty67 wrote:Mine, only one on a diesel, I suspect, was due to overheating. I am sure my mot guy left it running on its test and the fan never kicked in.
Ran it for about a year with the problem, sometimes it was ok sometimes pressurising, eventually it was pressurising all the time.

Yours, if not overheated, could be due to poor quality heads maybe or incorrect thickness head gasket. What metal are the heads made from?


Not sure what it’s made of but I bought it from the engine shop https://www.theengineshop.info/acatalog ... 065CX.html

Pretty sure mine doesn’t have head gaskets. Only water jacket seals..?




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Re: Another rebuild already??

Postby 123-jn » 11 Feb 2020, 16:07

Rebuilding is always an interesting thing. There is the measure test and test again route replacing all slightly worn items and cleaning everything spotlessly, new AMC heads and new non AMC valves, new hoses new pipes, etc etc
then there is the wang a couple of new heads on and hope rebuild. My first rebuild was a mixture of the two. I stripped it to tiny pieces measured and cleaned , new bearings , polished crank, new rings honed bores,new oil pump, BUT I reused the heads which tested OK. BAD IDEA, A year later one head cracked so I replaced it in situ with another second hand one after fitting new guides etc. BAD IDEA The next year I had to remove the engine again the other head had gone, cracked in the same place as head 1, near the spark plug hole and under the head bolt pad. This time I decided to go 2.1 so rebuilt an old 1.9 block with 2.1 internals again everything new apart from one used AMC head and One late VW head both had guides and valves and seats cut. BAD IDEA, a few weeks later the VW head cracked internally between a valve port and a waterway. Not sure if pressing in the guides caused a weakness? So due to lack of funds another spare VW head was reconditioned and fitted. shhh (its still running 2 yrs later)
The Moral of this story is take it out and strip it completely to bits measure everything and replace all bearings, thrusts, seals,core plugs,rings,pumps,pipes, and both the heads with AMC castings but dont use the valves that come with them. The old VW valves are best if serviceable. May as well change lifters and use telescopic pushrod tubes as this makes liter trouble easier in future. Unfortunately you will often find that although your crank is good and in spec , the Camshaft is NOT. Doing it yourself it costs about 1000 for the bits and the time is yours. Oh and it is fun doing it yourself in the shed over christmas (twice)
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Re: Another rebuild already??

Postby itchyfeet » 11 Feb 2020, 19:21

Reads to me like you are not doing this yourself?

If this is the case and you are finding mechanics to do it for you you are going to struggle to ever get it fixed.

The reason is mechanics now days are not engineers, they just don't have the time or patience and if they did have the patience you would not want to pay the bill.
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Re: Another rebuild already??

Postby DoubleOSeven » 11 Feb 2020, 22:17

^^ yes. Have a go yourself, we’ll help you. Your bottom end is ok, top end rebuild. Follow itchy’s engine build notes.
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Re: Another rebuild already??

Postby LewisMac » 17 Feb 2020, 10:39

I would be keen to give it a go. Seems only right that I should know how to fix and maintain my own van.

Getting a sniff test done this week so will see what happens then go from there.




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Another rebuild already??

Postby LewisMac » 19 Feb 2020, 13:18

Ok so sniff test showed no exhaust gas was present in header tank.

Have given her another good bleed and after 40 miles the header tank is at min.

Expansion tank is overflowing and bleed rail empty’s when I shut her off.

Anything else I can try?

Noticing a few bubbles entering the header tank during bleeding process, this normal?


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Re: Another rebuild already??

Postby Swebby » 19 Feb 2020, 15:25

Dalek cap working?

E D I T

Sorry missed the bit about 2 new ones

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Re: Another rebuild already??

Postby tencentlife » 19 Feb 2020, 15:31

I have an article that explains what's going on and how you can tell a fire ring leak, which it sounds like you have, from a pressure cap problem.

https://intrepidoverland.com/bad-coolan ... ad-gasket/

Chemical tests are not always reliable, and they're unneeded because the symptom set is unmistakeable.

And here's a bit on how to treat fire rings so you don't go thru this all over again:

https://intrepidoverland.com/the-fire-ring-cure/

You said you had new heads, if they were new AMC castings you can pretty much rule out cracks. The OEM heads were very prone to cracks at high mileages but the AMC's are heavily built up in those areas so cracks are almost unheard-of. Fire ring leaks, though, are very common, it's a hard part of this engine to get right and reliable. My second article above will help ensure success.
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Re: Another rebuild already??

Postby LewisMac » 19 Feb 2020, 17:58

tencentlife wrote:I have an article that explains what's going on and how you can tell a fire ring leak, which it sounds like you have, from a pressure cap problem.

https://intrepidoverland.com/bad-coolan ... ad-gasket/

Chemical tests are not always reliable, and they're unneeded because the symptom set is unmistakeable.

And here's a bit on how to treat fire rings so you don't go thru this all over again:

https://intrepidoverland.com/the-fire-ring-cure/

You said you had new heads, if they were new AMC castings you can pretty much rule out cracks. The OEM heads were very prone to cracks at high mileages but the AMC's are heavily built up in those areas so cracks are almost unheard-of. Fire ring leaks, though, are very common, it's a hard part of this engine to get right and reliable. My second article above will help ensure success.


Great article, thanks for that!


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Re: Another rebuild already??

Postby LewisMac » 19 Feb 2020, 18:10

Fire ring also referred to as the “O RING”?


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