Hot engine, newly rebuilt - Troubleshooting - VWDiesel.net The IDI, TDI, and mTDI source.

• Hot engine, newly rebuilt by ORCoaster on 30 Aug, 2017 20:51
• I recently purchased a 1981 Caddy and have noticed that it tends to run about 20 degrees hotter than the thermostat rating.  I have verified the gauge temp in boiling water and the opening temp of the thermostat.  Both seem to be correct.
  
  Yesterday it was a little warmer than usual here on the Oregon coast and I saw 230 F on the gauge.  I pulled over and opened the overflow/reservoir tank and noticed spurts of air in the return stream of antifreeze.  Crap loosing a head gasket I thought.
  
  So today I pulled the injectors and measured the compression in each cylinder.  Figuring one would be low if the gasket was going.  Well all four measured at 500 psi.  So I thought maybe it gets warm and then it leaks. 
  
  I buttoned it up and started it and no air in the system and it was cycling the fan fairly often but the gauge only showed 210 F. 
  
  I then decided that if this was a rebuilt engine what are the chances that the 1000 mile re-torque got done.  I removed the valve cover and went all around the head and they were all at 90 nM or 67 psi.  I retightened them on the proper pattern and started it up and it still runs hot.
  
  I have a lower temp thermostat that I guess is the next thing to do.  But I was wondering if there is any other thing that comes to your mind that I might check as well.  My brain is toast from being in the sun all day. 
  
  Shopping for possibilities  Thanks
• #1 by acidtonic on 30 Aug, 2017 21:07
• If it has powersteering, the ps belt drives the water pump. Looks like the pump can be driven by the main vbelt but on mine it didnt turn the pump well enough and the power steering belt was missing when purchased.
  
  Also when you change the Tstat you can put your fingers up inside the housing and feel the water pump blades. If you reach around and turn the pump by hand you can make sure they spin and if rusted you can feel it.
  
  Head is warped on mine and it only leaks when warm so Im in the process of sorting that out on my build.
  
  Also bad injection pump timing can cause overheating as can bad valve clearances. Other things to think about. Good luck.
  
  Sent from my LGMS550 using Tapatalk
  
  
• #2 by vanbcguy on 30 Aug, 2017 22:16
• Yup, check to see if the wp is actually spinning, they used a freewheel pulley on the alt belt with the actual drive pulley on the PS belt stock. And the impeller spinning on the shaft is another common one!
  
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• #3 by ORCoaster on 30 Aug, 2017 23:58
• I did check on the belt tightness on the WP.  I was also sourcing out why the voltage was jumping around on the volt gauge.  I will report back on the WP after the thermostat switch.  There is plenty of water moving in the system.  The hose into the reservoir is pretty strong at 1000 rpms and is flowing at idle.  So pretty sure the WP is doing its job. 
  
  Timing was checked a bit ago and is solid at 95 mm.  No clack from the engine, sounds like a sewing machine at around 1200 rpm.  Very smooth, easy to start.
  
  Might have to check on the valve clearances though.  Those might be off.  Going to change the oil and filter as I don't think that has been done yet after the rebuild.  Engine may only have 1000 miles on it and I have put half of them on since I got it going in July.
  
  Thanks for the extra head thinks.  Might just be still breaking in?
  
• #4 by air-cooled or diesel on 31 Aug, 2017 07:34
• so it has 1 belt, running from crank to alt to water pump? if voltage isnt right it may be belt, just because you figure you have (enough) water flow doent mean its right, its running hot^^right? yes thats your current problem. i never had a problem with system burping, for me it just burps as thermo opens up, then add water, seems for some reason you have air in system. ?burp system with one side jacked up? as theres a post on that as some people have had that problem.
• #5 by ORCoaster on 31 Aug, 2017 11:30
• Air-Cooled or Diesel, Yes it only has the one belt as you describe.  Belt is new, alternator was acting up in the recent past because the excitor wire was broken at the plug.  I fixed that but the wire is very brittle and may be breaking contact somewhere else.  I plan to replace the wire in total and get that variable out of the equation.
  
  The flow of water through the system couldn't be better in my opinion.  It is as good as my other diesel if not better.  I should also state that this Caddy has a brand new radiator installed on it as part of the rebuilt engine.  So I am doubtful the capacity to cool the system is a problem either.  But when I swap the thermostat I am going to back flush everything in case some piece of a gasket is lodged in the system somewhere.  I have seen that happen in the past.  Even one of those metal like seals on a bottle of something could be hiding in there. 
  
  So I need not burp the system, I know what you're trying to tell me and the system is totally full to capacity. 
  
  Thanks for the thoughts on this. 
• #6 by ORCoaster on 01 Sep, 2017 23:25
• OK, the promised follow up
  
  I replaced the thermostat with a lower temp one and now I only see about 195 on the gauge.  One on the dash is near mid-point.  I saw no movement of the impeller when I stuck my fingers in the thermostat hole.  I could turn the pulley and the impeller was right with it.  I back flushed the radiator but nothing came burping out. 
  
  The system was refilled, engine run and raced to get the air out and then cycled the fan a couple of times.  Seems stable so I will leave it alone for now.  My first thought of blown head gasket does not seem to be the case. 
  
  All Cylinders register at 500 psi.  The hoses don't get pressurized when it it running. 
  
  I changed the oil and the filter and I will just have to be satisfied all it well until something more drastic happens.  I wouldn't have been too concerned of the temp at first but it does run hotter than the Rabbit I have.
  
  Still have to solve the alternator problem.  Only charging at 12.5 or so volts and barely any amps under full load of headlights, fan and radiator fan being on.  Swapped voltage regulators and no change.  Maybe time for a new alternator?
   
• #7 by RustyCaddy on 03 Sep, 2017 20:03
• Is the waterpump impeller the oem or aftermarket blade design? Seems like some folks have suggested the non-oem was less efficient in moving coolant; i have never used one. You probably thought about that already but just in case. Good luck sorting it out.
• #8 by ORCoaster on 03 Sep, 2017 20:38
• Not sure entirely on Water Pump.  It looks like it got changed out by the PO when the engine was rebuilt.  Metal impeller showing in thermostat opening.  New green gasket all around.  So that leads me to think it was changed from OEM.
  
  Flow at 1200 rpm is pretty stout going into the reservoir so I don't think that is an issue.