Operating Temperatures

Home Forums MGTD Kit Cars VW Based Kits Operating Temperatures

Viewing 18 posts - 1 through 18 (of 18 total)
  • Author
    Posts
  • #301245
    John Simion
    Participant

    @johnsimion

    HappyJack’s posting about a new carburetor was going off into the issue of operating temperatures, which got me started worrying and researching my own situation, since my own car here in Las Vegas stop-and-go driving in 115 degree air temps has caused me to hit 230 degrees more than once.  I figured it would be better to start a new thread than to hijack HappyJack’s thread.

    I shouldn’t worry TOO much according to these sources:

    The Gene Berg web site says you’re too hot if you’re over 230 degrees.  I’m borderline, assuming my temp gauge is accurate, although Rob and Dave say the temp gauges understate temperatures.  See http://www.geneberg.com/cat.php?cPath=5_116.  Berg says he has a publication on cooling that is valuable for owners of kit cars, but I don’t see any way to order it.  Do any members have this?

    Hays VW Repair web site says, “Proper oil temperature for any vehicle is between 220 and 240 F.”  Well, that’s comforting.  See http://haysvwrepair.com/operating-temperatures/

    The REASON the operating temperature is important is the potential breakdown of the lubricating qualities of oil above 240 degrees.  Using synthetic oil might potentially moot that issue since it breaks down at higher temperatures:

    Aircooled.net says, “Since synthetic oil has better heat transfer qualities than dino oil, your internal engine temperatures will be lower. Things like bearings, especially, will not operate at as high of a temperature as a result. The wider range of temperatures that synthetic oil can withstand is well suited for the air-cooled VW engine. With head temperatures normally between 300-350 degrees, synthetic will not breakdown while lubricating the valve train components at the heads. The better lubricating properties of synthetic in general will lead to a longer engine life as well. On average, when synthetic oil is run in an air-cooled VW engine, head temperatures stay the same, but engine oil temps reduce by anywhere from 10 to 15 degrees. This is in identical engines that have all the correct cooling tin in place, and are not suffering from overheating to begin with. Important note: Do not run synthetic to fix a hot running engine. Find the real reason it’s running hot, and fix it!”   http://www.aircooled.net/synthetic-vw-oil/

     

    In addition, Rob and Dave suggest that using 91 octane fuel without ethanol in it would reduce temperatures.  See  http://www.vw-resource.com/overheating.html

    It would appear that I’m due for a synthetic oil change and a fillup with premium gas without ethanol in it.  Those are simple preventative measures, and as little as I drive, it’s a minimal expense worth giving a try.  As long as I’m not going over 230 degrees anyway, I don’t see the need to work on putting tin between the engine and exhaust/muffler.

    #301247
    KentT
    Participant

    @kentt

    Note the caveat on the air-cooled.net article you cite — “that have all the proper cooling tin in place.” Most TDrs do not – they lack the tin and rubber seals/flaps that keep the hot air that is exiting the bottom of the engine and the exhaust heat out of the engine compartment, allowing thahott  air to be sucked in by the fan and recirculated. If most of your driving is outside the stop-and-go traffic of cities/towns not having that tin and seals is not as critical — since the airflow underneath and around the car when moving will pull that hot air away from the engine. However, sitting at a traffic light, or inching through traffic, that hot air will rise up into the engine compartment without something to block it.

    Early FF TDr on 69 VW pan
    Slowly coming back from the ashes...

    #301256
    HappyJack
    Participant

    @happyjack

    Great observations — and good idea John about starting a new thread —

    I guess I’ll switch to synthetic oil AFTER I check out my engine cooling system….  Thanks John for the citations and references and Kentt, great observation on how we TDr’s (and the companies who made the kits) tend to not pay attention to proper engine tim and engine compartment seals.  I guess we are expected to only cruise through beautiful Autumn countryside at 55 MPH and never sit in stop-and-go traffic — yea, right!!

     

    Happy Jack

    #301257
    edward ericson
    Participant

    @edsnova

    More tin is better. You can seal the top of the motor from the bottom/exhaust with a little ingenuity. I think Jack’s car has rubber flaps.

    Bridget has small gaps at the sides but ran cool enough (according to my Gene Berg dipstick thermo-warning device) no matter what. And the engine still does, according to the guy what bought it from me two years ago…

    #301260
    Royal
    Participant

    @royal

    Remember when tires had inner tubes?   Well, I have a large one on hand and am planning cutting it up and seeing about making a better seal in/for Migi.  Before the show in Virginia Beach.

    #301283
    KentT
    Participant

    @kentt

    Roy, I suggest you fold your strip of inner tube to make two layers or flaps. Put the fold to the outside, and fasten it to the body. Then take a dull screwdriver, paint stirrer,  putty knife or similar and carefully work the bottom flap down underneath the engine tin. Leave the top flap laying on top of the engine tin. This will give you something very similar to the factory seals. Should you want to buy instead of fabricate the seal, I suggest you get one for the VW busses that used upright engines (1971 and earlier). They would be too long but easily cut to correct length. I haven’t bought one in many years, but they’re likely a bit pricey. I have an old headliner tool that is flat, dull, with rounded corners that works well to cram the flap of the rubber seal down below the tin, then you can slide it around the perimeter and the round corners don’t catch on the flap, feeding it down where it belongs.

    Early FF TDr on 69 VW pan
    Slowly coming back from the ashes...

    #301285
    Royal
    Participant

    @royal

    Thanks Kent, good idea.

    WILCO!!

    #301286
    Toller
    Participant

    @toller

    The original builder did a poor job of fitting the splash pan around the engine tin. I used the curvature of tin as a mold and added a number of layers of fibreglass to reduce the size of the gap. I then purchased the following from CIP1 which I was able to slide between the tin and splash pan without removing the engine as they recommend
    https://www.cip1.ca/ProductDetails.asp?ProductCode=VWC-111-813-705-D Something you may want to consider in lieu of fabricating something from an inner tube

    David B Dixon
    Port Perry ON CA
    Sabine

    #301308
    Ed Service
    Participant

    @eddy

    An interesting article regarding VW oil temperature  !  http://haysvwrepair.com/operating-temperatures/

     

    #301309
    Ed Service
    Participant

    @eddy

    I’m sorry!  I didn’t notice until now that the original poster had posted a link to the above site!

    #301322
    Ed Service
    Participant

    @eddy

    #301323
    Ed Service
    Participant

    @eddy

    Maybe we are worrying way to much about 215-220 degrees?   https://540ratblog.wordpress.com/

     

    #301324
    John Simion
    Participant

    @johnsimion

    I think Eddy is right.  Too much worry.  The Beetle’s original design dates back to the 1930s and oils likely weren’t as good back then, so perhaps there was more need to worry about engine failure due to overheating back then.  Today’s oils are likely a lot better, particularly the synthetic ones.  Apparently today’s oils can stand the heat.  The article Eddy cited refers to normal operating temperatures up to 250 degrees, and he tested the oils at up to 275 degrees.  The author noted that the main harm of 275 degrees was the need for shorter intervals between oil changes, not imminent risk of engine failure.

    I don’t know about the rest of you, but the State of Nevada won’t even let me drive my car more than 5000 miles a year on my current registration, and more likely I’ll never drive more than 2000-3000.  And most of those miles are in cooler weather, because NOBODY wants to drive a convertible when it’s 110 degrees outside.  So it would appear that if I just change my oil once a year, I don’t have much to worry about from those occasional days when the engine reaches 230 degrees.

    #301360
    John Simion
    Participant

    @johnsimion

    New information.  I was trying to understand how the VW cooling system worked when I discovered the probable cause of my heating issues.  I could feel strong puffs of very hot air coming out by the #2 cylinder, with no apparent duct there.  The exhaust was tight, so I traced this to the heat riser, which was unprofessionally installed by someone else, probably the idiot who put in my Weber progressive.  I attempted to screw it down tighter and now the puffing is much weaker, but I can still feel it.  I can see the edge of the gasket and it’s twisted and not in proper position = unfixable.  Therefore I ordered new gaskets for the heat riser, and while I was at it, I also ordered a new rear tin that lacks all the holes in it except for the heat risers (the existing one had holes for the heater that I took out and another set of large holes for ???.  Closing those holes will keep most (not all) of the exhaust heat out, and fixing the heat riser ought to reduce cylinder head temps and maybe even let the car run better — although I had thought it was running pretty good anyway.

    #301361
    Paul Mossberg
    Keymaster

    @pmossberg

    I’m not advocating this, as I know it flies in the face of all accepted VW cooling principals.

    I have a 1776 in my TDr. The cylinder tin (upper and lower), and the rear tin (the sort of separates the top end from the muffler) are installed. No other tin is installed. And the engine compartment is not sealed. I’ve not seen any problems in traffic or on the highway.

    Again, I know that is not recommended.

    With the prior engine, a 1641, I did a couple of 4th of July parades in NJ with no overheating problems.

    Now, when a damn field mouse built a nest under the cylinder tin (over the left rear cylinder), I learned you can travel about fifty miles at highway speeds, with no air flow at all over a cylinder, before you burn a hole through the head. 🙁

    Paul Mossberg
    Former Owner of a 1981 Classic Roadsters Ltd. Duchess (VW)
    2005 Intermeccanica Roadster

    If you own a TDr and are not in the Registry, please go to https://tdreplica.com/forums/topic/mg-td-replica-registry/ and register (you need to copy and paste the link)

    #301362
    Paul Mossberg
    Keymaster

    @pmossberg

    Oh yeah, one other thing…

    I don’t have a temp gauge installed. But I have shot at the head and oil pan with an infrared temp gauge and have been with teh norms.

    Ok, two other things…

    Perhaps this is stating the obvious, but oil temperature and head temperature are two different things. If you have a temperature gauge on your dash, make sure you know what is being measured.

    Paul Mossberg
    Former Owner of a 1981 Classic Roadsters Ltd. Duchess (VW)
    2005 Intermeccanica Roadster

    If you own a TDr and are not in the Registry, please go to https://tdreplica.com/forums/topic/mg-td-replica-registry/ and register (you need to copy and paste the link)

    #301363
    John Simion
    Participant

    @johnsimion

    Paul, the guy who is my “new” mechanic prepares and races sand rails, and he says that my car is just about like a sand rail in that the engine is just sitting there, wide open underneath.  I suspect my engine is like yours.  The only tin I have is on the fan, the cylinders, and the rear tin.  Air can freely move from the front to the back and from the sides to the back.  On my car, the trunk/hood has a 15″ diameter opening that is covered by the spare, but that leaves a 1″ gap between the tire and the trunk/hood that’s almost 360 degrees, plus air also can circulate through the openings in the wheel itself.  That’s a lot of circulation.  This guy is telling me that I shouldn’t have any overheating problems at all.  That makes sense to me once I cap off the hot exhaust gas that’s currently entering the engine area through the heat riser.  This is not just air that’s hot because it just cooled the engine, this is very hot exhaust gas, and not a small amount of it.  It makes sense that the hot exhaust gas would cause overheating a lot faster than warm air from the cooling system entering the engine compartment.

    #301371
    Paul Mossberg
    Keymaster

    @pmossberg

    My Duchess is st up the same way John. Big hole under the spare tire.

    The guy that did the final build on my 1776 is a VW Micro Bus fan and has decades of experience with VWs. He said I have nothing to worry about. So I don’t. 😉

    Paul Mossberg
    Former Owner of a 1981 Classic Roadsters Ltd. Duchess (VW)
    2005 Intermeccanica Roadster

    If you own a TDr and are not in the Registry, please go to https://tdreplica.com/forums/topic/mg-td-replica-registry/ and register (you need to copy and paste the link)

Viewing 18 posts - 1 through 18 (of 18 total)
  • You must be logged in to reply to this topic.