wit's end

[damienk]

Thanks! I will try that. It is tan indeed, I remember. I thought it would be a lot more complicated than just one wire from A to B. I think I'd rather replace the whole wire unless that's a bad idea, as it is easier to run a new wire connected to the old one than to inspect the existing one (it goes through very, very hard to access places).
So tomorrow, new gauge wire, and... I don't know what else to do with the exhaust situation.
Anybody knows what the smoke is? or how to check if the hot pipe went bad?

[hanleyclifford]

Is your hot section constructed with galvanized pipe?

[hanleyclifford]

This is the better style fitting.

[hanleyclifford]

If this is a raw water cooled engine that has ben running with a thermostat for any length of time I would operate under the assumption that the block or other castings are at least partially plugged. It is quite possible for an engine to exhibit good water flow and good surface temp readings and yet be overheating in areas of the castings that are plugged. The water simply takes a preferential flow thru the remaining open passages, the surfaces over which can look good. I recommend an acid flush and a change to cast plumber's fittings where practical. Omit the thermostat for now and put a valve on that bypass.

[Administrator]

Looking at the way the red hoses neck down under the hose clamps, it looks to me like there is a size mismatch.

Bill

[hanleyclifford]

Looking at the way the red hoses neck down under the hose clamps, it looks to me like there is a size mismatch.

Bill

I noticed that too. My guess is that the heater core called for 3/4" so that's what was used. The return fitting at the front of the manifold is one of those horrible brass, machined 1/2"NPT to either 1/2" or 5/8" hose. As has been pointed out that plumbing plan is not standard. I think I see the attempt to extract maximum heat from the engine to benefit the heater. This arrangement imposes a burden on the pump especially if this is a raw water cooled engine.

[JOHN COOKSON]

Starting at the temperature sender, follow the single wire, usually tan, to the instrument panel where it connects to the 'S' terminal of the temperature gauge. Carefully inspect the condition of the insulation every inch of the way especially where it might touch anything metallic. Any damage to the insulation should be repaired with electrical tape at least. I won't ask you to replace the entire wire yet..

One ohm meter lead on the center terminal of the sending unit and one on the body of the sending unit. You'll find out real quick if there is a short to ground.
I'm not usually in favor of shotgun parts replacement but in this case it might be easier to skip the diagnostics and buy a new sending unit and gauge and run a new wire between them and be done with it. See post #29.

Part #2:
Get the exhaust unwrapped and see where the leak is.

TRUE GRIT

[HOTFLASH]

Temp sender?

In pic (#26) I noticed the teflon tape on what looks like the the temp sender. My understanding is that usually the install instructions say not to use any goop, seal or tape when screwing that into the port in the head, and that doing so can mess up the "sending" function. Maybe that is why the temp gauge is not working.

Mary

[JOHN COOKSON]

In pic (#26) I noticed the teflon tape on what looks like the the temp sender. My understanding is that usually the install instructions say not to use any goop, seal or tape when screwing that into the port in the head, and that doing so can mess up the "sending" function. Maybe that is why the temp gauge is not working.
Mary

One ohm meter lead on the body of the temp sending unit one lead on the head. You'll find out pronto if the sending unit is electrically connected to the head. It may be necessary to poke the probe through any paint or corrosion.

TRUE GRIT

[ndutton]

About those street ells

I notice that you are using the most restrictive of fittings. Why not try using straight connections to the manifold or at least cast style plumbers street fittings.

I propose a cast female elbow with a close nipple to provide the male thread is far and away less restrictive than cast street ells. One look at the opening in the male end of a street ell compared to a close nipple should make it obvious.

Quick calculation after I made some measurements: the I.D. of a ½" close nipple is 0.645" which translates to 0.327 sq. in. cross section. Compare to the I.D. (0.490") and cross section (0.188 sq. in.) of a ½" street ell male end. The street ell has only 58% of the cross section compared to a female ell + close nipple at its greatest restriction.

The only advantage I can see for using a street ell is maybe physical height but it comes at a big hit in terms of flow.

[hanleyclifford]

Hawkeye Neil

I propose a cast female elbow with a close nipple to provide the male thread is far and away less restrictive than cast street ells. One look at the opening in the male end of a street ell compared to a close nipple should make it obvious.

Quick calculation after I made some measurements: the I.D. of a ½" close nipple is 0.645" which translates to 0.327 sq. in. cross section. Compare to the I.D. (0.490") and cross section (0.188 sq. in.) of a ½" street ell male end. The street ell has only 58% of the cross section compared to a female ell + close nipple at its greatest restriction.

The only advantage I can see for using a street ell is maybe physical height but it comes at a big hit in terms of flow.

Good observations here by Neil. In selecting fittings for this application I have found over the years that another consideration has to be taken into account - strength. The female plumber's 90 does indeed offer more cross sectional area than the street but requires the use of the yellow brass machined close nipple which becomes the weakest link in the assembly. It is anodic to the 90 and cathodic to the casting both of which relationships set up galvanic cells. In addition the close nipple is physically weak and prone to vibration. On balance the street 90 presents only one galvanic cell and is much stronger physically than the close nipple. I have actually known the brass close nipple to fail in an A4 manifold. Good thing a 1/2" NPT tap was aboard. And one other thing - I always bore out and port the street which substantially reduces the cross sectional difference versus the nipple. If you do use the nipple/female 90 configuration I advise the use of a steel or iron close nipple which still leaves you with one galvanic cell but a lot more strength. Of course, if you go to FWC the problem goes away.

[ndutton]

Maybe I can help

Here are a couple of hints some members may find helpful:

[the yellow brass machined close nipple] is anodic to the 90 (female elbow) and cathodic to the (manifold) casting both of which relationships set up galvanic cells. If you do use the nipple/female 90 configuration I advise the use of a steel or iron close nipple which still leaves you with one galvanic cell but a lot more strength.

If there's a concern over dissimilar metals or galvanic cell, the normal preventive measure is to install a sacrificial zinc. West Marine carries them in a variety of configurations and sizes, pencil zincs in particular for engine related installations. This is known and accepted as effective protection of dissimilar metals concerns and is exactly why heat exchangers have provisions for zincs.

In addition the close nipple is physically weak and prone to vibration. I have actually known the brass close nipple to fail in an A4 manifold. Good thing a 1/2" NPT tap was aboard.

If there is engine vibration sufficient to damage a brass close nipple, there are bigger problems to resolve than the nipple material. That said, size matters. This discussion is not about the lengthy and therefore fragile 1/8" nipples common on the A-4 for water jacket drains and oil pressure senders.

With the perceived concerns resolved perhaps we can return to flow considerations.

[ndutton]

Damien,
How's it going? We're needing an update.

[Dave Neptune]

d, re the exhaust smoke. If it is coming out from under the "wrap" it can be a couple of things. If the wrap has gotten wet from anything it can take a long time to "boil" off, a very long time! If it is indeed exhaust it should smell like it, so a quick sniff test.

If it persists and does not smell like exhaust I'd peel it off and take a look at the pipe. If it is fresh "galvanized" pipe it will take a while for the galvanizing to "burn" away, this is why black pipe is preferred.

Dave Neptune

[hanleyclifford]

Here are a couple of hints some members may find helpful:
If there's a concern over dissimilar metals or galvanic cell, the normal preventive measure is to install a sacrificial zinc. West Marine carries them in a variety of configurations and sizes, pencil zincs in particular for engine related installations. This is known and accepted as effective protection of dissimilar metals concerns and is exactly why heat exchangers have provisions for zincs.
If there is engine vibration sufficient to damage a brass close nipple, there are bigger problems to resolve than the nipple material. That said, size matters. This discussion is not about the lengthy and therefore fragile 1/8" nipples common on the A-4 for water jacket drains and oil pressure senders.

With the perceived concerns resolved perhaps we can return to flow considerations.

Let me be more specific: A pencil zinc in the block of a RWC A4 will not protect a yellow brass close nipple atop the manifold.