Thermostat housing connector?

[JimG]

I finally got around to removing my thermostat (original, late model) and dismantling/cleaning/assembling it, thinking it might account for my cool running engine (gauge never moves even though the sender and gauge pass the diagnostic tests). I verified it opens at 140, and was about to put it back in when I noticed the right angle water inlet on the cover was severely resticted, by what looked like the same sort of gunk the thermostat had all over it. When I reamed it out on my drill press, I actually got lots of metal chips - I don't thing I got the fitting itself, as I used an undersized drill bit. Is this fitting INTENDED to act as a throttle, or does salt water just produce some goop that can look metalic?

[Don Moyer]

JimG,

It appears that a restriction had been installed in the inlet fitting to your thermostat housing.

Universal published a technical bulletin describing this process in the late seventies which was intended to enhance the flow of water in through the "T" fitting in the center of the water jacket side plate on engines where the cooling jackets were partially blocked. They actually recommended filling the hose barb part of the fitting with lead and then drilling a 1/8" hole through the lead.

Removing the restriction should definitely warm up your engine. If it runs too warm after removing the restriction, you may have to flush your block, head, and manifold, which is probably what one of your prior owners should have done.

Don

[JimG]

Thanks! I thought I was seeing things - and it did look like lead shavings. Is there a note on how to perform the flush?

[Don Moyer]

JimG,

The following procedure is based on the instructions contained in our flushing kit. There is also a version of the instructions contained in chapter 2 of our service and overhaul manual.

PRELIMINARY STEPS:

1) Remove starter and alternator.

2) Remove the three 1/8" pipe-threaded water jacket drain plugs. Two of these plugs are in the block (one is located at the forward end of the block beside the starter, and the other is located beside the distributor base). The third plug is in the lower rear corner of the manifold.

NOTE: 1 If the cooling system has not been serviced in many years, the plugs may have to be drilled out. If, after drilling out the plugs, the threads cannot be cleaned up with an 1/8" pipe tap, the drain hole(s) can be drilled out to 7/16" and threaded using a 1/4" pipe tap. Pipe taps and replacement 1/4" brass pipe plugs are available at most hardware stores.

3) Probe into each drain with a coat-hanger-sized wire to insure that they are open. If the drain on the manifold is clogged, it will be virtually impossible to open it without removing the freeze-out plug nearest the drain and probing the drain from inside the cooling jacket. While the drain in the manifold is not used to inject pressure water, as in the case of the drains in the block, it is still preferable to open the drain if at all possible.

FLUSHING THE BLOCK:

1) Install an 1/8" pipe-threaded 6" long brass nipple in one of the drain holes in the block and an 1/8" hex-headed brass pipe plug in the other block drain.

2) On early model engines, use a 1/8" brass 45 degree street-el (provided in kit) to facilitate reaching the drain hole behind the distributor.

NOTE 2: On late model engines, the 6" nipple can be left installed in the aft block drain after the flushing operation is complete to facilitate draining the block for winterizing or other servicing (use a 1/8" brass cap to close the end of the nipple). On early model engines, there is insufficient space for the nipple after the alternator is reinstalled; however, the 45 degree elbow can be left in place with an 1/8" hex-headed pipe plug installed to make subsequent draining somewhat easier.

NOTE 3: Early model engines have a cast iron crossover tube between the head and manifold which makes it difficult to flush the block and head separate from the manifold. In some cases, this cast crossover tube has been replaced with a rubber hose and 90 degree fittings. If this is the case on your engine, you may be able to install a discharge hose on the fitting on the head to be run overboard. You can then proceed with the following steps as in the case of a late model engine.

Steps 3 through 7 apply only to late model engines.

3) Remove the thermostat housing, both fittings, and the thermostat.

4) Install a 3/8" brass street-el in the outlet of the thermostat housing (the side marked "MAN"), and a 3/8" pipe plug in the inlet (the side marked "WP").

5) Reinstall the thermostat housing, but leave the thermostat out until after flushing is complete.

7) Install bushings on the end of the 6" nipple in the aft block drain as necessary so as to be able to install a swivel type garden hose fitting. It's also very convenient to install a small ball valve before the garden hose fitting so that you can stop/start the pressure from the hose for more aggressive flushing.

8) Flush the block until the effluent from the discharge hose is clear.

9) Move the 6" nipple to the other block drain, and flush that end of the block until the effluent of the discharge hose is clear.

FLUSHING THE MANIFOLD:

1) Remove the 1/2" fitting at the rear discharge of the manifold. Inspect and clean the 1/2" pipe thread opening as necessary.

2) Connect a garden hose to the rear outlet of the manifold for overboard discharge. A 1/2" male pipe thread by 3/4" male garden hose fitting is ideal for this purpose.

3) Install a second garden hose fitting to the front (inlet) of the manifold. Connect a garden hose to this fitting and flush the manifold with as much water pressure as possible. As in the case of the block, it's a good idea to install a ball valve between the garden hose fitting and the manifold to enable you to stop/start the pressure from the hose.

4) When flushing is complete, remove garden hoses and all flushing fittings. Reinstall the thermostat and reassemble the rest of the cooling system.

Don

[JimG]

I'm a little confused by the instructions. What is the reason for removing the drain from the manifold if it isn't used for the flushing process? Also, I assume the thermostat MAN fitting is the exit port for the flushing?

[JimG]

Also, what should happen to the hose that normally connects to the thermostat housing (from the T-connector) during flushing - seems like it will be another outlet for the flush.

[Don Moyer]

JimG,

The answers to your questions:

1) What is the reason for removing the drain from the manifold if it isn't used for the flushing process?
A: Simply to keep it functional as a drain.

2) I assume the thermostat MAN fitting is the exit port for the flushing?
A: True.

3) What should happen to the hose that normally connects to the thermostat housing (from the T-connector) during flushing - seems like it will be another outlet for the flush.
A: It is another outlet for the flush (hopefully to reverse flush the diverter cap and "T" fitting itself). After the initial flush, the hose can be reconnected for the rest of the flushing operation.

I appreciate your third question. I'll tweak the instructions a bit to be more clear on this point. Writing a flushing procedure is sort of like writing a procedure for mowing one's back yard. There are so many details and variables that you're never quite sure you're finished.

Don

[JimG]

Anytime you need an idiot proof reader, I'm available...thanks!