What temperature?

[Administrator]

At Jonathan Welch's suggestion, here's an opportunity to participate in a poll regarding your engine's temperature when fully warmed up.

Bill

[Jesse Delanoy]

y'know, it's funny sometimes ...

When I bought my '77 Catalina 30, with original RWC A4, 9 years ago, it ran pretty consistently around 180 warmed up, under load. Not so hot as to be problematic, but hotter than I would like. I tried everything I could think of. Pressure flushes. Acid flush. Opened up the side plate and cleaned out the gunk. Put a restriction on the bypass. One season, on advice of a local mechanic, I blocked off the bypass entirely. Replaced the thermostat. All with no results.

Three seasons ago, the old girl finally gave up the ghost, and I installed a Moyer rebuilt replacement engine. I thought, finally, I'll be operating at the desired temperature. No such luck. Still running right around 180.

Along with many other projects along the way, I undertook to replace the three mismatched gauges on my instrument cluster. The gauges (and associated sending units) of course did not get replaced with the engine - my mechanic simply installed the old ones on the new engine. The oil pressure gauge and ammeter went in quite easily, but I COULD NOT GET the old temperature sending unit out of the cylinder head. It was stuck in, absolutely fast. I tried with every vise grip I could get my hands on, and succeeded only in wearing the hex-head on the sending unit down to a near perfect circle. I gave up on it for about a year and a half, and just lived with the old gauge.

This spring, during re-commissioning, I was thinking about having the old sending unit drilled out - not sure if this was possible since there's only about 3 inches of space between the front of the engine and the front of the engine compartment (access is from the top down). But I had the engine warmed up during an acid flush, and wondered if I could get the sender out while everything was nice and hot. I put a vise grip on it as tight as I could possibly muster, and whacked it about three times with a rubber mallet, and sonofagun if it didn't loosen right up. I was thrilled.

Anyway, to make a long story short (I know ... too late!), I put in the new sending unit and temperature gauge I'd been sitting on for a year and a half, and guess what? Engine is now running consistently at 160 - 165 under load.

I'm guessing there was a long-standing mismatch of temperature gauge and sending unit - the original SW gauge had been replaced with a cheapo at some point prior, and I bet the sending unit had never been touched. These two items must be matched up, or the gauge readings are suspect. I spent eight years worrying about an engine that probably was never overheating.

[roadnsky]

160º at 1700rpm in calm water at 5.5k. (Oil at 40psi)

[Mark S]

I answered the poll "160 degrees" based on what our gauge read last year when it was operating. I still haven't got it working this spring. I think the engine is operating a little cooler now than last year, based on what it feels like when I touch it, because of some off-season improvements and maintenance: (1) I cleaned the thermostat which was really ugly; (2) I installed the by-pass valve which I close when I think the engine ought to be warmed up; and (3) I gave it two vinegar flushes. Of course it could simply be a five to ten degree difference in May and September ocean temperatures.

Mark S

[rigspelt]

...wondered if I could get the sender out while everything was nice and hot. I put a vise grip on it as tight as I could possibly muster, and whacked it about three times with a rubber mallet, and sonofagun if it didn't loosen right up. I was thrilled.

That really is one sweet feeling of relief. Happened the other night with a throughull that finally turned out.

[Dave Neptune]

Too cool 130 degrees??

I have been using a valve in the bypass line for 26 years now on a raw water cooled application. Yes I do run a bit cold (130 degrees) however I run easy until the temp has come up, after that I run at 2000 RPM's with the Indigo 3-blade.
One thing I do check is when I turn off the A-4 after a long run I switch the ignition back on after about 4-5 minutes and she reads about 140~150 degrees which is approximately what the core of the engine is actually running at. I think the water bypassing the block cools the "thermostat corner of the head" just a bit affecting the reading on the gage when not using a thermostat.

Dave Neptune
1970 E-35MkII original A-4 still "ticking"

[Capn Tom]

what temperature?

I've got one for "me hardys"! A previous owner (#1 or #2) removed the thermostat. He ran a hose from the t-fitting that's supposed to run to the t-stat and instead ran it to the manifold. The hose also has an on-off valve in it. I assume he had overheating problems and thought this was a solution? I don't use the hose in the on position.
My engine used to run up to 160; sometimes a little higher until I acid flushed. It then started running at 110. I always flush the engine with fresh water after using it (it is raw water cooled) to get rid of any salt.
Sidenote: Last week I replaced the riser because corrosion ate right through it.
Should I leave it alone or put back in a t-stat?

[MikeB.330]

between 170 and 180 just like a freshy should.

[67c&ccorv]

[QUOTE=Jesse Delanoy;14474]The oil pressure gauge and ammeter went in quite easily, but I COULD NOT GET the old temperature sending unit out of the cylinder head. It was stuck in, absolutely fast. I tried with every vise grip I could get my hands on, and succeeded only in wearing the hex-head on the sending unit down to a near perfect circle. I gave up on it for about a year and a half, and just lived with the old gauge.

"Firstly, vice grips are not for removing nuts or bolts - they are a last ditch attempt when a proper fitting wrench or socket is not at hand and you absolutely must remove the bolt/nut. Try gently heating the area around the bolt or thread with a propane torch and then put some effort on a proper fitting wrench."

This spring, during re-commissioning, I was thinking about having the old sending unit drilled out - not sure if this was possible since there's only about 3 inches of space between the front of the engine and the front of the engine compartment (access is from the top down). But I had the engine warmed up during an acid flush, and wondered if I could get the sender out while everything was nice and hot. I put a vise grip on it as tight as I could possibly muster, and whacked it about three times with a rubber mallet, and sonofagun if it didn't loosen right up. I was thrilled...I'm guessing there was a long-standing mismatch of temperature gauge and sending unit - the original SW gauge had been replaced with a cheapo at some point prior, and I bet the sending unit had never been touched. These two items must be matched up, or the gauge readings are suspect. I spent eight years worrying about an engine that probably was never overheating.

"Yes, gauges and their senders must be matched or the readings will be innacurate!"

1967 early model Atomic 4 with Dole thermostat runs steady 140 degrees on Great Lakes freshwater after warmup on my C&C Corvette.

[sastanley]

oil pressure poll?

Hi Bill,

Great idea..I also like roadnsky's additional details for his particular situation provided.

Here's mine: 160-165 at 1,500 RPM. For now that's my 'favorite cruising speed'. The speedo says 4.6 knots , but it is new and not calibrated.

What about a similar poll for typical oil pressure? I dunno how well that would work since that reading probably fluctuates moreso than temp, but I would assume most have a 'standard range' they see at their favorite cruising speed which could be detailed in a topic reply after the poll entry.

Edit - update time.

So, now that I have been using the boat a little more I have been experimenting with the bypass lever.

With it wide open, I am closer to that 165 F & it fluctuates a bit...it'll go above 170F and then down to 160. When I close the bypass all the way, it is much more stable at 155-160F, but I also notice not as much exhaust flows out of the pipe either. I would assume this is because until the thermostat opens, only the small amount of water sneaking thru the closed t-stat is making its way to the exhaust. Is there any other place water can get to the manifold besides thru the t-stat bypass or the t-stat itself?

[Administrator]

Got it, Shawn!

Bill

[bcooke]

My understanding is that raw water cooling is usually around 180 and freshwater cooling is around 160.

Does that sound about right?

My freshwater cooled A4 runs right at 160 no matter what sort of load its under.

[MikeB.330]

bcooke, you have that backwards. 160 for sea water cooled and 180 for fresh water cooled is what you're looking for. Your's is a bit cool for a fresh water cooled engine. Are you sure you have the correct Tstat instaled?

[alberg]

Water Temp

At operating RPM's of 1550 my temp is 145 deg on my VDO matched 4 gauge unit. However after running and then idleing it drops to 100 deg.

Alberg

[ne57301]

I'm still getting used to the cleaned out engine.

My raw water cooled used to run at around 180-190 with frequent spikes, back off the throttle and it would cool right down. Now it stays pretty solid at 155-165 except a MAJOR spike a week ago. I limped the last .5 mile of a 30 mile delivery (wow was that lucky!!) and when I went back to troubleshoot it was fine. I figure after all the cleaning I did last winter a piece of scale wedged somewhere unfortunate (manifold exit?) and settled again when it was shut down for a while. I'll continue to watch the gauge - and for steamy exhaust.