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Cooling issue

kevin_z

kevin_z

Regular Contributor
1995 454XL. FWC. 900 hrs. History: Replace risers and raw water pumps April 2016. Boat ran great all summer. did cap,rotor,plugs Dec 2016. Ran as usual. Just drained coolant, replaced thermostat (CRUR026007) and VDO temperature sending unit (CRU22701). Now the helm gauges read 185 at idle at dock. Used my IR gun. Fill neck PT:147 STBD: 141...Thermostat housing before ts, PT: 148 Stbd: 150...After ts, PT: 166 STBD 159... Inboard manifold, PT: 170 STBD: 175.... Outboard riser, PT: 93 STBD: 94. Again, gauges read 185. Before any work was started, gauges read 165-170. Any ideas, or what am I missing??
 
On the thermo housing gasket, did you use the one with brass rivets?

Stewart-Warner #334-AD temp sender specs

TEMP OHMS TOLERANCE

100 412 +/- 62
145 230 29
190 151 14
235 123 6.5
280 56 3
 
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The rivet issue isn't applicable to your "newer" (later than Mark-IV) block.....in addition, assuming the gauges are ok, you are seeing too little resistance with the "high reading"....

single or dual helm installation???
 
single station is key....VDO, in the past 30 years or so, switched over to the 'American standard'.....nominally, that means the sensor is built with a thermistor that will provide 240 Ohms at the MIN reading and 33 ohms at the MAX reading....for temp, that's typically 120 deg F and 240 deg F respectively....

As far as accuracy goes the few specs I've seen usually have an hourglass curve with best accuracy (+/-10 deg F) usually occurs ~180 deg F....and it expands (less accurate, going either hotter or colder.....

Since you have new (& correct version/style) senders, and a 'hot error' the senders are the suspects.....you can use resistors (in place of the sender units) to check the gauge and the wiring.....or just accept it....
 
I just took the new senders out a put the old ones back in. All temps with IR is the same as above, however the helm gauges are now reading 165. SO, wrong sender. Now try to get a return. Thanks for the ideas, information. Is there a part # for a suitable replacement other than the CRU22701? Mako, thanks for the Ohm #s. I will do that test soon. Not anal, but never been towed or come in on one.
 
DD: Excellent data find...and thanks for sharing!!

Kevin: i may not be anything 'wrong' with the senders, it may be the range of your temp gauges....and the sensors' outputs not 'matching' their needs....what is the MIN and MAX values shown on your temp gauges?
 
My VDO gauges read from 100-220 degrees Fahrenheit. The new sender has 120 degrees Celsius and a stamped number 801/1/16 and 6-14
 
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I just got a email from VDO and they no longer offer temp senders for the 220f gauges. They said a standard ignition p/n TS-6 or a KEM manufacture p/n TW-3
 
There you go.....a suboptimal sender.....for your application/installation.

Cant tell you if the numbers they offered will do it either.....if the old ones are working, I'd be inclined to keep them....glad you resolved that one...
 
I went to NAPA and their part # TS6469 for the KEM TW-3. Bought one and a wire adapter for the new sender. Installed it and the port engine tempeture gauge is reading what the IR gun is reading on the fill neck. Will get out today and buy one for the STBD engine.
 
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