TR Plus 4 : NO ENGINE LEAKS
by Bob Nogueira at the eMog Pub

After one year and one month and three teardowns, I can now say I have a Plus 4 that does not leak a drop of oil. I would write the full story of the
'Rebuild from Hell' but I'm afraid it would consume so much bandwidth the internet would come to a stop. Knowing that there are some in the pub like me, who save messages with tech advice, I will edit it down to only the points that actually achieved an oil tight engine.   
 

1. Many of the bolt holes in the block are open to the inside of the crankcase, use permetex thread sealant on all bolts. 
2. Greg Solow's modified rear scroll seal really works, is cheaper than the rubber seal conversions and does not require modifying the crankshaft.
3. If you have the main bearing journals line honed be sure to have the machine shop surface the bottom of the block. The problem here is to rebore the mains they start by cutting down the journal a bit to make the bore smaller, they then rebore it to the correct size. This means that the journals will be about .010 inches lower that the block at the oil pan mating surface allowing oil to escape.
4. Don't use the oil pan gasket that comes in the gasket kits. Make your own from NAPA's rubberized cork gasket material. It is much stronger and actually conforms to any irregularities while the paper gasket does not. 
5. If you have the block vat cleaned replace the aluminum oil galley plugs on the front and rear of the block. The cleaning process eats away the aluminum from the inside leaving only a paper thin plug that while looking  okay, could never stand up to 70 PSI.  (The only source I found was The Roadster Factory. It is not listed in the catalog but they have them in the shop and will sell you a pair.) 
6. Don't just scrape the old gasket off the surfaces, use brake cleaner on the surfaces before applying any gasket sealer. This is especially true of the newer silicone sealers, which will not stick to the metal if it has any oil on it at all. 
7. Make sure the machine shop uses sealant on the freeze plug that caps the rear cam bearing. 
8. If the front crank pulley hub is anything but perfect, use a SpeediSleeve on the hub. 
9. If oil is leaking from the bell housing don't assume that it is the result of a leaking rear main seal. The rear of the oil pan meets the top of the sheet metal bell housing cover plate at the block. If the oil pan is leaking at the rear (see #3) the oil can be sucked into the bell housing because the flywheel is acting like a centrifugal fan.
10. NAPA sells a ultraviolet dye for oil (can be used in any fluid). Once added. Any leak will glow bright yellow under ultra violet light. It is so good that you can see oil on your fingers that you can't feel. It is great for tracing the oil leak to it's source.
11. Throw out the felt that comes in the gasket kits and use the JHSII method: one inch by four inch strips of cotton tee shirt soaked in Indian Head Gasket Shellac. It is not only much easier to install but seals better.
12. If you have an Aluminum valve cover, throw out the cork gasket in the kit and make your own using NAPA's rubberized cork gasket material. The aluminum covers do not match the head fully, being slightly over sized. The  gasket in the kit is rather narrow and when used with a aluminum cover have very little mating area with the head.

And there you have it. I hope someone can benefit from my year of frustration.  Bob  

13. WEBMASTER WATCHPOINT I am adding one other cause. If the engine venting is blocked, you will blow oil out the dipstick hole. A TR4 engine vents through a crankcase ventilation system, typically utilizing a breather pipe located on the rocker cover or oil cap, which allows excess pressure from the crankcase to escape and be drawn out by the engine's airflow, preventing damage from excessive buildup; this system is often referred to as a "breather" system.   You will have othjer symptoms, such as the oil loss you mention.