12 replies to this topic

[ChrisLC]

Hi all, I am running the LJ XU1 style plumbing for my heater in my LC, where both pipes come off the RHS of the lower thermostat housing. It don't work. Engine has a 186 head although it could be older. The little hole below the thermostat bolt hole on the left, when was that introduced? I suspect mine is either blocked, or not there at all.

Thanks

 

 

 

 

 

 

 

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[claysummers]

Will be a 149 or 179 head. HR on had the extra hole I believe but could have been HD.


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[Dr Terry]

Yes, the hole appeared in the first of the HRs.

 

EH/HD had the 2-bolt thermostat housing & HR onwards had the 3-bolt type.

 

Dr Terry

[claysummers]

The early heads still had the three tapped bolt holes for some reason. A friend says he tried drilling out the front of the head to enable flow but I believe it ended in disaster.


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[ChrisLC]

The early heads still had the three tapped bolt holes for some reason. A friend says he tried drilling out the front of the head to enable flow but I believe it ended in disaster.


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Shit, that don't sound good. I wonder what happened, any idea? Hopefully I have the hole, and it's just blocked. Thank you.

[Dr Terry]

Back in the day, the exchange engine guys used to drill out every head in that spot & then plug it with an Allen grub screw.

 

If the engine went into an EH or HD the plug was left in situ.

 

If the engine was to go into a later car (HR onwards) then you simply remove the plug.

 

Dr Terry

[claysummers]

Shit, that don't sound good. I wonder what happened, any idea? Hopefully I have the hole, and it's just blocked. Thank you.

Ok, so not disaster, but just drilling out is not sufficient to create the necessary pressure differential to get any flow is what he has told me. I need to look at the heads I’ve got to understand.


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[Dr Terry]

It's been a long time since I've looked at this closely, but from memory that small hole goes to a channel which exits thru a hole in the head gasket. This goes straight to the water pump & allows plenty of pressure differential & flow for the heater operate.

For example in an HQ 6-cyl there is enough pressure differential to push the coolant thru both the manifold & heater (in series) & the heater worked well.

Dr Terry

[claysummers]

Looking at 202 head confirms this (2811930). 7420081 head from 179 I have which is an L head, open chamber. This doesn’t have the passage down through block to water pump inlet although the 179 block does have the corresponding passage.

So drilling a hole in the front of the head just goes in to the heads water jacket same as the thermostat outlet. If you want to get any flow between the later thermostat housing lower outlets you will need to use a later head, HR on.


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[Dr Terry]

Looking at 202 head confirms this (2811930). 7420081 head from 179 I have which is an L head, open chamber. This doesn’t have the passage down through block to water pump inlet although the 179 block does have the corresponding passage.

So drilling a hole in the front of the head just goes in to the heads water jacket same as the thermostat outlet. If you want to get any flow between the later thermostat housing lower outlets you will need to use a later head, HR on.


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I think the problem my have been that he drilled thru too far. If you drilled in to a specified depth & then from the head gasket face upwards I believe that everything would work.

 

Dr Terry

[claysummers]

Dr Terry, there doesn’t appear to be enough meat in the casting of the head I am looking at to do this. The202 head has more iron in that area. This head is from an early 179 M54091, part number as above.


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[claysummers]

Chris,
The flow can be achieved by running heater hoses from the outlet on the top of the water pump (needs to be drilled out), and use a brass union screwed in to threaded hole on the other side of the thermostat housing, or at the rear passenger side of the cylinder head. Generally one hole will contain the temperature light switch and the other a blanking plug.
Cheers
Clay


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[ChrisLC]

Thanks all. Will check it all out over the weekend.