At the risk of hijacking your "look what I bought today thread" (sorry for my impertinence) I thought I'd redirect it back to the original subject matter as I've completed and done at least some preliminary testing on the bypass thermostat mod linked below....

https://landroverforums.com/forum/di...38/#post924037

 

Just got kicks I decided to do a leak down test on the 25x,xxx mile 99 4.0 block I just stuffed with 4.6 internals. All new bearings, 4.6 cam, inline thermostat mod.

Passed the leak down test with flying colors. Figured since there was a 3/8 port on this why not give it a go. I don't register any pressure. This is obviously post thermostat and it's not open yet but I should still get excess pressure since there is the bleeder valve.

Will continue to keep an eye on it. Unfortunately it sits too high to close the hood for an at speed test. Reads zero until about 5 psi. She's not budged from zero.

No reports of slow heat down into the 20s. The drivers heated seat shorted and burn some of the upholstery a year or more ago. If she had slow heat the admiral would certainly let me know immediately. Like all good disco owners who don't do their own repairs, she reports any changes in so sound, performance or functionality. This helps me to take care of issues before they become big issues many times.

 

Normally they don't build pressure till been hot and running long enough that the thermal expansion builds the pressure.

 

If today wasn't the first rainy day we've had in over a week if I'd have taken the good off and ran it down the road. With the thermostat mod, 4 or 5 year old OEM radiator and an O'Riley's water pump it's hard to get this thing to budge above 180 on a 70 degree day.

I have an extra oil pressure gauge at the shop with electric pickup. I can perhaps TEE this into the the ridged line coming it of the top of the coolant overflow. I can then run a pressure test after a long run.

 

What were your findings? It seems the post was deleted as clicking the link shows an invalid thread error.

 

So much this. Too many folks don't 'listen' to their vehicles until it is too late.

On the other hand I suppose we, the people who inhabit brand/model specific message boards, are the outliers.

 

my 2c: In my 04, I have the OEM cooling setup including T-body heater, 'grey' 180 t-stat, all newer hoses, Xerex green borate + silica free AF, used but recent OEM H20 pump and rad. I have an aftermarket electronic temp sensor on the outlet 'hot' side. It registers on cool and hot days usually 190-195 (within a few degrees compared to ultragauge reading). The highest temp I have seen is 209 sitting in traffic very hot day with AC running which dropped immediatly once moving again. Remember though, this is the coolant temp leaving the engine. It should be soaking up the heat. I feel that the OEM setup is doing it's job drawing heat away from the block/heads like it should. And, I think it has the capacity to absorb more heat if needed. +10 or even 20 degrees from my baseline does not concern me. All of the head gaskets I have replaced have been in high mileage disco's with less than stellar care...

 

Yes, the original cooling setup works FOR A WHILE as the cheap components deteriorate, clog the too-narrow radiator channels with sediment. Design meant to feed the parts/service shop with its poor longevity. There is no feature built-in a radiator to fully flush deposits inside. Once I removed the plastic tanks and was able to clean all the guts; but re-closing it failed. I wish there was a chemical that really works dislodging deposits.