Can I use a early model head on a late model?

[MikeDSmith]

I need to replace my late model head. I have an early model used engine that someone gave me. Since I have a fresh water cooling system with the indigo marine temp adjuster, I don't use a thermostat.

Would it be OK to use the early model head on the late model block?
The early model head does not have a hole for temprature sending unit. Is there any other place that it could be mounted?

[Don Moyer]

Mike,

It's OK to use an early model head on your engine as long as you're using a
"circulating" type of cooling system with full flow through the block and
head (which I assume you are).

Don

[MikeDSmith]

The early model does not have the hole for the temperature sensor. Is there another place to put the temprature sensor?

[Don Moyer]

Early model cooling systems should have a recirculating loop from the rear outlet on the manifold to the raw water inlet to the water pump. Water temperature sensing elements should be located in that recirculating loop to reflect the operating temperature of the engine, usually by the addition of a "T" fitting to accommodate the size threads used on the sensing element.

You can see such a "T" fitting in the instructions in the attachment with a "ghosted" 1/2" threaded temperature sensing unit in one of the branches of the "T". The instructions are actually intended for installation of a Dole type thermostat housing, but the "T" fitting itself and the recirculating loop are the same even without the thermostat.

Don

[Pater]

Early A4 without a thermostat

Hi Don, The Early engine I have doesn't have a thermostat, just a close nipple to the manifold, and a temp. sensor fitted into one side of a T and an outlet barb to the exhaust on the other. Where do I get a "Dole" thermostat? Do I need one?

[Marian Claire]

Pater: My understanding is that you do not need a T-stat on an early model if you install the proper recirculation loop. This is what I use on the MC. T out of manifold. One side is temp sensor the other is to another T. One side of the second T goes to the wet/dry connection on the exhaust. The other loops back and ties in with the raw water feed to the water pump. This loop has a ball valve to control the amount of hot water being recycled. You can adjust the valve to get the temp you want under the different operating conditions. Hope that helps. Dan S/V Marian Claire

[Don Moyer]

Pater,

Many early model folks successfully use a manual re-circulation loop as described by Dan.

Without a thermostat OR manual re-circulating loop back to the inlet of the pump, your early model engine will run as low as 110 degrees in most areas of the country (which is a bit on the cool side).

I'll attach a set of instructions that accompany our Dole thermostat plumbing kit so you can see what's involved in installing a thermostat, which will also work if you decide to stay with the manual approach. You simply install a second "T" fitting over the rear outlet of the manifold instead of the Dole housing. The Dole thermostat and housing are available on our online catalog.

Don

[Pater]

Early A4 temp question

First things first I've got to get a reliable temp gage & sender. The original had a thin copper tube in a wire wrapped jacket that screwed into one side of the T. Then I'll get the ball valve as you and Dan suggest and plumb up the recirculator loop. Thanks Don for the help and the encouragement.