Author |
Message |
hlwimmer Samba Member
Joined: May 29, 2002 Posts: 533 Location: concord, calif.
|
Posted: Sun Apr 24, 2011 8:02 am Post subject: overheating oil issue in 1776 |
|
|
hi all: i've been putting the vintage-speed 1776 back into action recently now that the weather is improving and have run into an issue: overheating. sorry for the long post.
unfortunately, my engine builder is unavailable and i might have to resort to tearing into it myself -- which is potentially dangerous as i'm more the "designer" than the "builder" type, but i'm about out of options here in norcal... thus the post to the community.
the motor is a 1776 with an 010 dizzy and dual zeniths. i think the cam is a 110, but i can't recall. i have a porsche-356 style bypass oil filter and oil-pressure and cylinder-head-temp gauges installed. the shroud is a doghouse style and the cooling system is otherwise stock, but i recall the fan being the "welded/balanced" type. the engine runs well. the carbs run a teeny-bit rich, but not terribly.
the problem: after a run up the freeway, the engine overheats to the point where (i suspect) the oil is thinned so much as to reduce pressure below the 10PSI spot. at this point, the motor is blisteringly hot (block / dipstick) but the head temps read about 200-250deg via the gauge... i've recently been running a deck-lid standoff and it's helping, but not completely solving the issue (i also have a 'vert decklid).
it's gotten to the point that i've had to run progressively crazy-heavy oil (presently trying 60W racing).
i'm thinking either:
(1) i have no idea what i'm talking about and should just find someone who can fix it properly. solution: find someone ... (ideas? i'm in the SFBay area -- specifically concord).
(2) the timing might have drifted causing some overheating issues. solution: re-time. (a little harder since i'm running a repop OT pulley, but...)
(3) a previous mishap with the cam/crank gear threw shavings into the oil stream and the cooler is plugged (backstory: shortly after the motor's maiden voyage, the helical gears went south when on the road to a show throwing shavings into the oil -- which looked like metallic paint. the builder replaced with "stronger" straight cut gears which have worked fine since, but now wondering about the cooler... not sure if the builder replaced it on the 2nd build). solution: replace oil cooler and shore-up everything in there. (i believe the hoover bit is installed)
(4) with the dual carbs, the engine just needs more air for both combustion and cooling. solution: find a way to get more air in there... like the standoff.
(5) the design of my CSP competition exhaust keeps hot pipes too close to the heart of the beast. solution: deal with it as the exhaust was so damn expensive (or maybe replace the heater boxes with j-tubes for a bit more space/air-flow down there -- i never run the heat).
thanks for any insight or wisdom that you can lend...
motor pix: https://www.thesamba.com/vw/gallery/pix/798575.jpg
(i've just order a jay-cee standoff from CB to replace my home-made one.) |
|
Back to top |
|
|
RockCrusher Samba Member
Joined: August 03, 2010 Posts: 4596 Location: Parkesburg, PA
|
Posted: Sun Apr 24, 2011 8:15 am Post subject: |
|
|
Do you have all the stock tinware in place? And I mean ALL of it....
RC _________________ [email protected] Please use email for all general inquiries.
I will be happy to speak to anyone who has a serious inquiry (meaning real potential business for RC enterprises) or a parts order. Due to machining noise causing missed calls all calls will be returned promptly. |
|
Back to top |
|
|
hlwimmer Samba Member
Joined: May 29, 2002 Posts: 533 Location: concord, calif.
|
Posted: Sun Apr 24, 2011 8:41 am Post subject: |
|
|
RockCrusher wrote: |
Do you have all the stock tinware in place? And I mean ALL of it....
RC |
yes. |
|
Back to top |
|
|
Max Welton Samba Member
Joined: May 19, 2003 Posts: 10697 Location: Black Forest, CO
|
Posted: Sun Apr 24, 2011 8:41 am Post subject: Re: overheating oil issue in 1776 |
|
|
hlwimmer wrote: |
the motor is blisteringly hot (block / dipstick) but the head temps read about 200-250deg via the gauge... |
If you have the VDO CHT, these readings may be wildly inaccurate.
Last summer I was working through mixture-control issues with OTs reaching the mid 240s and the VDO CHT was only reading around 200º.
Max _________________ 1967 Type-3 Fastback
Under the Knife https://shoptalkforums.com/viewtopic.php?f=24&t=151582
Home Stretch https://www.thesamba.com/vw/forum/viewtopic.php?t=767836
Last edited by Max Welton on Sun Apr 24, 2011 8:46 am; edited 1 time in total |
|
Back to top |
|
|
71_1302 Samba Member
Joined: January 19, 2008 Posts: 133 Location: ~547ft. above sea level.
|
Posted: Sun Apr 24, 2011 8:43 am Post subject: |
|
|
Sorry to read about your overheating troubles. You have a beautiful engine and car.
A couple of things come to mind, but I have questions first. What weight of oil were you using when the engine first started overheating? What were your cold and hot oil pressure readings with that initial weight of oil? What are these readings now with 60W oil? Just curious, since you appear to have a dual sender in your engine compartment.
Also, definitely verify your timing. This is the most likely suspect to me, since you appear to believe it may have changed at some point.
Best,
-S _________________ 71' Super Beetle, now departed. |
|
Back to top |
|
|
hlwimmer Samba Member
Joined: May 29, 2002 Posts: 533 Location: concord, calif.
|
Posted: Sun Apr 24, 2011 8:58 am Post subject: |
|
|
71_1302 wrote: |
Sorry to read about your overheating troubles. You have a beautiful engine and car. |
thanks... lots of folks have had a hand in helping to get it to this state.
71_1302 wrote: |
What weight of oil were you using when the engine first started overheating? What were your cold and hot oil pressure readings with that initial weight of oil? What are these readings now with 60W oil? Just curious, since you appear to have a dual sender in your engine compartment. |
started with castrol 20W50 and switched to swepco 20W50... at initial startup, all weights were fine, but with 20W50, the oil thinned so quickly that the sender fired in just a few miles. presently, with the 60W and the decklid prop, it seems to be OK. i'm going to try to go back to 20W50 with the prop and hope that might be a fix... not happy about running such heavy oil.
71_1302 wrote: |
Also, definitely verify your timing. This is the most likely suspect to me, since you appear to believe it may have changed at some point. |
will check once i figure out how to do it... i'll likely need to measure out the crank pulley and put markings on it. then, i'll need to figure out what the idea timing might be. |
|
Back to top |
|
|
Max Welton Samba Member
Joined: May 19, 2003 Posts: 10697 Location: Black Forest, CO
|
Posted: Sun Apr 24, 2011 9:20 am Post subject: |
|
|
hlwimmer wrote: |
71_1302 wrote: |
What weight of oil were you using when the engine first started overheating? What were your cold and hot oil pressure readings with that initial weight of oil? What are these readings now with 60W oil? Just curious, since you appear to have a dual sender in your engine compartment. |
started with castrol 20W50 and switched to swepco 20W50... at initial startup, all weights were fine, but with 20W50, the oil thinned so quickly that the sender fired in just a few miles. presently, with the 60W and the decklid prop, it seems to be OK. i'm going to try to go back to 20W50 with the prop and hope that might be a fix... not happy about running such heavy oil. |
To answer 71_1302s question, you need oil pressure readings in PSI.
I agree on timing being a prime suspect, particularly if the exhaust is getting extremely hot.That is one of the signs of ignition timing that is not advanced enough.
A centrifugal-only distributor (your 010) should be timed at around 30º BTDC at around 3000 RPM (or whatever engine speed the timing doesn't advance any more).
Max _________________ 1967 Type-3 Fastback
Under the Knife https://shoptalkforums.com/viewtopic.php?f=24&t=151582
Home Stretch https://www.thesamba.com/vw/forum/viewtopic.php?t=767836 |
|
Back to top |
|
|
nsracing Samba Member
Joined: November 16, 2003 Posts: 9481 Location: NOVA
|
Posted: Sun Apr 24, 2011 1:11 pm Post subject: |
|
|
60W oil, huh? what is w/ the tranny oil?
Is this a high compression engine? Maybe your timing or too lean mixture. |
|
Back to top |
|
|
|