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Snoopy1971
Samba Member
Joined: May 15, 2020
Posts: 311
Location: Parkville, Maryland
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 Posted: Sun Jul 20, 2025 1:27 pm Post subject: Overheating Help |
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I need some assistance with my engine overheating.
Some background... It's a '68 Bug. When I got the car 5 years ago, it had an H case from a '67, with the bigger 85.5 pistons/cylinders to make it a 1585. Still has a non-doghouse fan shroud. Ran fine for 5 years.
Back in the spring, it broke down on me on a drive. Couldn't get above 65 MPH and once I saw the smoke behind me, I pulled over. Upon looking underneath the engine, there was a good amount of oil dripping out. Got the car home and let it idle a couple days later and could see oil dripping down onto the forward-most pushrod tube on the left side (so under #3). Thought maybe it could have been the oil cooler or seals. So tore the engine down and replaced the seals and even though the oil cooler seemed fine (it was aftermarket, not an original VW one), I replaced that also with another new aftermarket one.
While the engine was out, I also decided to replace the engine bay tarboard, put in one of those chrome firewall kits, replaced my throw-out bearing since it was out, and painted my fan shroud and engine tins.
Once the engine was all back together, I ran it outside of the car before putting it back in. Ran fine, let it sit and idle for like 20 minutes, with some revs here and there. No oil leaking, so figured the engine was ready to back in the car . Before putting it back in, I decided to do a compression test. Only #2 had good compression at 124. #s 1 & 4 were 97 and 90. #3, ZERO compression. So tore the engine back apart to discover a nice chunk taken out of piston #3.
So I ended up doing a top end rebuild on the engine. I got a rebuild kit from AA ... new cylinders and 88mm thick-walled pistons and new heads to up the size to a 1679. I put some Lucas 20W-50 Break-In oil in the engine.
Ran the rebuilt engine again outside the car and all ran fine. Once I got it back in the car, it wouldn't start. Or I should say it started, but would run for 2-3 seconds and die. After troubleshooting, I narrowed it down to the fuel pump. It was the early 60's dome topped type, but no VW and Pierburg identification on the side, so I assume it was an aftermarket one. I thought it odd and quite coincidental that the fuel pump worked fine and the engine ran outside the car a week or so earlier, but now it wouldn't run in the car, but OK, I guess it was a coincidence.
I ended up replacing the fuel pump with a rebuilt Pierburg square top one from Sparxwerks. Engine fired right up!!
So I took the car out to do a break-in session for the new rings. Went up and down a hill like 4 times in gear both ways. Was out driving it like 20 mins total, neighborhood roads, so about 25-30 MPH most of the time with a little bit up the 40 MPH for a min or so total. Upon returning home, I took the dipstick out and used a candy thermometer to take the oil temp ... It was 225°. After it cooled down a little, I then went to change the oil. I knew there would be a glitter party in the oil due to the rings, but the oil was super gray and really thin (see pic). I wonder if it was thin due to gas getting in it when the old fuel pump failed. But the oil didn't smell like gas at all.
So I changed the oil and put in some Valvoline 10W-40 synthetic blend. I used to just use conventional 10W30, but decided to try this oil due to some others using it and recommending it in some other forums/groups etc. So took the car out the next day and drove around locally for about 35 minutes, no more than 40 MPH .. .45 MPH for a few short bursts, and did crank it up to 65 MPH on one road for like 10 seconds.
When I got home, I took the temp again with the candy thermometer. This time it was 250°.
Isn't normal operating temp like 215°-ish or so? Why would my engine be overheating so much now, when it didn't before?
I have all the tins in place. Cylinder tins, the deflector tins under the cylinders, sled tins under the pushrod tubes, rear tin, the 2 small air deflector tins that go behind the cylinders on the underneath side.
Now I did forget to prop my decklid open with a large tennis ball like I usually do, but I can't see it having that much effect. It was like 85° out and humid yesterday.
I'm stumped ... any insight from anyone?
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bsairhead
Samba Member
Joined: October 08, 2008
Posts: 4496
Location: viroqua wi.
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| Posted: Sun Jul 20, 2025 2:33 pm Post subject: Re: Overheating Help |
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| Check valve lash 'cold' and timing. |
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Eric&Barb
Samba Member
Joined: September 19, 2004
Posts: 25988
Location: Olympia Wash Rinse & Repeat
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| Posted: Sun Jul 20, 2025 3:33 pm Post subject: Re: Overheating Help |
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Do a tune up first off.
Probably too thick of oil used causing too much oil pressure. That in turn makes the oil relief valve to shunt the oil away from the oil cooler.
Hope it works out, but seen too many top end rebuilds fail all too soon due to worn bearings giving out from new P&C pressure on them.
Do also get an oil bath air cleaner that is too small to do a good job, and hose clamps on both top and bottom of both fresh air tubes. When one of those tubes pops off, the head on that side gets a lot hotter and oil temp can shoot up 30F more.
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Bobs67vwagen
Samba Member
Joined: March 27, 2005
Posts: 400
Location: Eastern north carolina
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| Posted: Sun Jul 20, 2025 3:45 pm Post subject: Re: Overheating Help |
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| Is it possible for you to try a matched distributor to go with your carb instead of the 009. If your carb is a 34 pict-3 try a svda that goes with that carb and try to really dial in the timing so your engine runs as efficiently as it can at all speeds. In addition to that I would try to get more cooling air to the engine compartment., and of course keep a careful eye on valve clearance with a new top end. |
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Cusser
Samba Member
Joined: October 02, 2006
Posts: 33112
Location: Hot Arizona
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| Posted: Sun Jul 20, 2025 4:44 pm Post subject: Re: Overheating Help |
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1968 sedan so solid engine lid, but instead of 1500cc single port engine like 1968 had, you now have 1600cc dual port engine with a non-doghouse shroud and cooler.
When VW went to 1600cc dual port for 1971 year, not only did they go to doghouse shroud and oil cooling system, they used a vented engine lid. So you might have an air flow issue. Consider lid standoffs, a vented engine lid, or the tennis ball trick.
I'm in Arizona, and my own 1970 sedan has 1600cc dual port engine WITH doghouse cooling and the 1970 2-vent engine lid, and I still use lid standoffs.
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1970 VW (owned since 1972) and 1971 VW Convertible (owned since 1976), second owner of each. The '71 now has the 1835 engine, swapped from the '70. Second owner of each. 1988 Mazda B2200 truck, 1998 Frontier, 2014 Yukon, 2004 Frontier King Cab. All manual transmission except for the Yukon. http://www.thesamba.com/vw/forum/album_page.php?pic_id=335294 http://www.thesamba.com/vw/forum/album_page.php?pic_id=335297 |
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ashman40
Samba Member
Joined: February 16, 2007
Posts: 16592
Location: North Florida, USA
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| Posted: Sun Jul 20, 2025 5:17 pm Post subject: Re: Overheating Help |
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| Cusser wrote: |
1968 sedan so solid engine lid, but instead of 1500cc single port engine like 1968 had, you now have 1600cc dual port engine with a non-doghouse shroud and cooler.
When VW went to 1600cc dual port for 1971 year, not only did they go to doghouse shroud and oil cooling system, they used a vented engine lid. So you might have an air flow issue. Consider lid standoffs, a vented engine lid, or the tennis ball trick. |
Everything Cusser mentioned above.... and, did you check your compression ratio when you increased the engine displacement and replaced the heads?
Changing the displacement alone with no other changes will result in increased compression ratio. Higher compression ratio often means more power and hotter temps. Replacing the heads means the combustion chamber volume could be larger or smaller. Smaller volume means increasing the compression ratio. When you bore out the heads to accept larger diameter cylinders you increase the combustion chamber volume which results in a change in the compression ratio.
If you didn't check your compression ratio before putting the heads on I don't know what to tell you. Unless you can find someone that assembled the exact same parts you did and they can tell you their values and measured compression ratio I don't know of any way to confirm compression ration without actually measuring it with the heads off. The two numbers that are unique to each build... combustion chamber volume (in CCs) and the deck height (distance between the top of the piston at TDC and the top edge of the cylinder sleeve, in inches or mm).
As part of replacing the piston with larger displacement ones and the heads with new you should have checked/calculated the compression ratio and if needed add cylinder spacers between the case and the bottom of each cylinder sleeves to adjust it. Adding spacers increases the cylinder deck height and reduces the compression ratio to compensate for the increased displacement and/or the change in the combustion chamber volume.
Link
https://cbperformance.com/v/enginecalc.html
For a stock engine, you probably want to keep the compression ratio in the 7.0~7.5:1 range. Even if you drop the compression ratio a few decimal points, the increase in engine displacement will result in increased power over stock and still allow you to run cheap pump gas. If your compression ratio has risen higher you may need to run high octane gas to feed that engine's higher compression ratio. You may also need to retard the ignition timing to avoid detonation.
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AshMan40
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'67 Beetle #1 {project car that never made it to the road  }
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Snoopy1971
Samba Member
Joined: May 15, 2020
Posts: 311
Location: Parkville, Maryland
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| Posted: Mon Jul 21, 2025 4:48 am Post subject: Re: Overheating Help |
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| Cusser wrote: |
1968 sedan so solid engine lid, but instead of 1500cc single port engine like 1968 had, you now have 1600cc dual port engine with a non-doghouse shroud and cooler.
When VW went to 1600cc dual port for 1971 year, not only did they go to doghouse shroud and oil cooling system, they used a vented engine lid. So you might have an air flow issue. Consider lid standoffs, a vented engine lid, or the tennis ball trick.
I'm in Arizona, and my own 1970 sedan has 1600cc dual port engine WITH doghouse cooling and the 1970 2-vent engine lid, and I still use lid standoffs.
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Yeah I had a 1600 in it (or 1585, whatever ppl want to call it  ), and upped it a hair to 1679. Are you saying 1679 is too big to use a non-doghouse setup?
Yes I normally do the tennis ball trick ... I forgot it both days I took it out for a spin. I had been considering standoffs for a while, but not crazy about the big gap when it is time to wash the car. I do like the adjustable standoffs by Deano's VW that have the ability to open and close, but hate the loss of the decklid spring and the ability to open it and have it stay up on its own. I guess it's a tradeoff and something the owner has to deal with.
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Snoopy1971
Samba Member
Joined: May 15, 2020
Posts: 311
Location: Parkville, Maryland
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| Posted: Mon Jul 21, 2025 4:48 am Post subject: Re: Overheating Help |
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| ashman40 wrote: |
| Cusser wrote: |
1968 sedan so solid engine lid, but instead of 1500cc single port engine like 1968 had, you now have 1600cc dual port engine with a non-doghouse shroud and cooler.
When VW went to 1600cc dual port for 1971 year, not only did they go to doghouse shroud and oil cooling system, they used a vented engine lid. So you might have an air flow issue. Consider lid standoffs, a vented engine lid, or the tennis ball trick. |
Everything Cusser mentioned above.... and, did you check your compression ratio when you increased the engine displacement and replaced the heads?
Changing the displacement alone with no other changes will result in increased compression ratio. Higher compression ratio often means more power and hotter temps. Replacing the heads means the combustion chamber volume could be larger or smaller. Smaller volume means increasing the compression ratio. When you bore out the heads to accept larger diameter cylinders you increase the combustion chamber volume which results in a change in the compression ratio.
If you didn't check your compression ratio before putting the heads on I don't know what to tell you. Unless you can find someone that assembled the exact same parts you did and they can tell you their values and measured compression ratio I don't know of any way to confirm compression ration without actually measuring it with the heads off. The two numbers that are unique to each build... combustion chamber volume (in CCs) and the deck height (distance between the top of the piston at TDC and the top edge of the cylinder sleeve, in inches or mm).
As part of replacing the piston with larger displacement ones and the heads with new you should have checked/calculated the compression ratio and if needed add cylinder spacers between the case and the bottom of each cylinder sleeves to adjust it. Adding spacers increases the cylinder deck height and reduces the compression ratio to compensate for the increased displacement and/or the change in the combustion chamber volume.
Link
https://cbperformance.com/v/enginecalc.html
For a stock engine, you probably want to keep the compression ratio in the 7.0~7.5:1 range. Even if you drop the compression ratio a few decimal points, the increase in engine displacement will result in increased power over stock and still allow you to run cheap pump gas. If your compression ratio has risen higher you may need to run high octane gas to feed that engine's higher compression ratio. You may also need to retard the ignition timing to avoid detonation. |
Oh yes, I apologize ... I meant to to include this info in my original post and forgot.
Yeah I measured deck height and the CC in my old heads when I took them out and got a CR of 7.3. Actually, I didn't measure all 4 cylinders. I only measured #2. There was something odd about the 2 heads that I couldn't put my finger on at the time when I removed them. It wasnt until later when I noticed they had 2 diff numbers on them and I discovered a Samba thread from 2014 from somebody who had the same 2 numbers on his heads. Turns out my right side head was from a Type 3. I haven't measured all the CCs yet on them, but I will eventually because I am curious to see if they are diff sizes between the 2 sides. To the eye, it looks like the Type 3 head (right side, bottom one in pic), has a bigger CC.
Anywho, yes I measured my new setup. #s 1 & 3 had the same deck height, #2 was .002 more, and #4 was .002 more than #2. So #s 1 & 3 had a CR of 8.6, and #s 2 & 4 had a CR of 8.5.
So I should be running higher octane gas? ... 91 or 93?
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Snoopy1971
Samba Member
Joined: May 15, 2020
Posts: 311
Location: Parkville, Maryland
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| Posted: Mon Jul 21, 2025 4:50 am Post subject: Re: Overheating Help |
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| bsairhead wrote: |
| Check valve lash 'cold' and timing. |
Yep I did the valves before putting the engine in the car, but rechecking was on my list since it can change after a break-in.
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Snoopy1971
Samba Member
Joined: May 15, 2020
Posts: 311
Location: Parkville, Maryland
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| Posted: Mon Jul 21, 2025 4:52 am Post subject: Re: Overheating Help |
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| Eric&Barb wrote: |
Do a tune up first off.
Probably too thick of oil used causing too much oil pressure. That in turn makes the oil relief valve to shunt the oil away from the oil cooler.
Hope it works out, but seen too many top end rebuilds fail all too soon due to worn bearings giving out from new P&C pressure on them.
Do also get an oil bath air cleaner that is too small to do a good job, and hose clamps on both top and bottom of both fresh air tubes. When one of those tubes pops off, the head on that side gets a lot hotter and oil temp can shoot up 30F more. |
10W40 is too thick??
Yep, tuneup is on my list.
Actually I do have an oil bath filter that somebody gave me. It was on my list to clean it up and put it on ... I just didn't want to change too many things at one time.
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Snoopy1971
Samba Member
Joined: May 15, 2020
Posts: 311
Location: Parkville, Maryland
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| Posted: Mon Jul 21, 2025 4:55 am Post subject: Re: Overheating Help |
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| Bobs67vwagen wrote: |
| Is it possible for you to try a matched distributor to go with your carb instead of the 009. If your carb is a 34 pict-3 try a svda that goes with that carb and try to really dial in the timing so your engine runs as efficiently as it can at all speeds. In addition to that I would try to get more cooling air to the engine compartment., and of course keep a careful eye on valve clearance with a new top end. |
Yes my carb is a Weber 34 Pict-3. Actually I do have a rebuilt DVDA distributor (I believe its DVDA, not DVDA) that I got from VWNOS like 4 years ago ... just never put it on. Didnt want to put it on just yet as I didn't want to change too many things at once.
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Cusser
Samba Member
Joined: October 02, 2006
Posts: 33112
Location: Hot Arizona
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| Posted: Mon Jul 21, 2025 6:22 am Post subject: Re: Overheating Help |
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| Snoopy1971 wrote: |
| hate the loss of the decklid spring and the ability to open it and have it stay up on its own. I guess it's a tradeoff and something the owner has to deal with. |
I've dealt with that for 5 decades. At first, I made a "lid stick" out of wood, rested that on a bumper bracket.
Later I saw someone else doing this (photos) so I copied that. I "store" the screwdriver between the side firewall "cardboard" and the body.
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1970 VW (owned since 1972) and 1971 VW Convertible (owned since 1976), second owner of each. The '71 now has the 1835 engine, swapped from the '70. Second owner of each. 1988 Mazda B2200 truck, 1998 Frontier, 2014 Yukon, 2004 Frontier King Cab. All manual transmission except for the Yukon. http://www.thesamba.com/vw/forum/album_page.php?pic_id=335294 http://www.thesamba.com/vw/forum/album_page.php?pic_id=335297 |
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Bobs67vwagen
Samba Member
Joined: March 27, 2005
Posts: 400
Location: Eastern north carolina
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| Posted: Mon Jul 21, 2025 7:13 am Post subject: Re: Overheating Help |
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| Snoopy the best distributor for that carb is the svda not dvda. The dvda if I am not mistaken has a vacuum retard which was for emissions and I do not think you want to mess with that. My other thought on your situation that would be easy to do would be to get a later decklid that has vents for additional air flow. I know the early 70s lids will fit your car. Make sure all of the tin work has no voids where hot air from below the tin can enter the engine compartment. It would be much easier for you to try some of these things to see if you can bring the running temperature down a bit. If you do the dizzy swap and can only static time it. Take it to a shop and have them time it at speed so you get the most efficient engine operation at all speeds. Do put the oil bath air cleaner on they are the best for these motors. Don't give up you may be able to correct your issues. |
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vamram 
Samba Member
Joined: March 08, 2012
Posts: 8035
Location: NOVA
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| Posted: Mon Jul 21, 2025 7:50 am Post subject: Re: Overheating Help |
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I'm no expert but 8.5+ is a pretty high CR. At the very least, you're probably running lean for your new compression numbers (which would run hot) and should go w/bigger idle and main jets on your 34-3. Aside from the CR, do you know the compression PSI per cylinder? You can run the DVDA as an SVDA - simply don't connect the retard port and keep it plugged on the carb, then time it as you would an SVDA.
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goober
Samba Member
Joined: May 03, 2003
Posts: 1239
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| Posted: Mon Jul 21, 2025 8:06 am Post subject: Re: Overheating Help |
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My experience with the H case is that if over heated the 10mm cylinder studs like to pull out.
It looks like the head/cylinders were leaking at the bottom. Did the heads torque down properly?
If the heads aren't torqued down properly or loose it'll be sucking air and that means lean. |
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Snoopy1971
Samba Member
Joined: May 15, 2020
Posts: 311
Location: Parkville, Maryland
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| Posted: Mon Jul 21, 2025 10:24 am Post subject: Re: Overheating Help |
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| vamram wrote: |
| I'm no expert but 8.5+ is a pretty high CR. At the very least, you're probably running lean for your new compression numbers (which would run hot) and should go w/bigger idle and main jets on your 34-3. |
Yeah I thought it was high, but when I posted here about it a month ago, those who responded to me thought it was fine, so I ran with it 
https://www.thesamba.com/vw/forum/viewtopic.php?t=803792
I dont know what size my idle jet is, but when I took my main jet out to check it recently, I discovered it's a 135. I thought I read somewhere that std size for a 34 pict-3 was 127.5. I guess I'll have to look into bigger sizes.
| vamram wrote: |
| Aside from the CR, do you know the compression PSI per cylinder? |
I have no idea what it is or how to calculate it.
| vamram wrote: |
| You can run the DVDA as an SVDA - simply don't connect the retard port and keep it plugged on the carb, then time it as you would an SVDA. |
Thx for the tip!!
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Snoopy1971
Samba Member
Joined: May 15, 2020
Posts: 311
Location: Parkville, Maryland
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| Posted: Mon Jul 21, 2025 10:27 am Post subject: Re: Overheating Help |
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| goober wrote: |
My experience with the H case is that if over heated the 10mm cylinder studs like to pull out.
It looks like the head/cylinders were leaking at the bottom. Did the heads torque down properly?
If the heads aren't torqued down properly or loose it'll be sucking air and that means lean. |
How can you tell from the pic of my engine that the head/cylinders are leaking at the bottom ... there is no leaking going on, as I'm not seeing any oil leaks. Yes heads were torqued down to spec when I assembled.
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my3bugs
Samba Member
Joined: June 18, 2003
Posts: 876
Location: Moreno Valley
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| Posted: Mon Jul 21, 2025 10:35 am Post subject: Re: Overheating Help |
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he was talking about the old heads .
that is some kind of liquid BRAIN oil !!!
Last edited by my3bugs on Mon Jul 21, 2025 11:27 am; edited 1 time in total |
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chrisflstf
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Joined: February 10, 2004
Posts: 4070
Location: San Diego
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| Posted: Mon Jul 21, 2025 11:24 am Post subject: Re: Overheating Help |
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I assume you are sticking the candy thermometer in the dipstick hole? Does it smell hot? Can you hold the dipstick? Any oil pressure gauge?
That first pic of oil change does not look good. Did you clean the cylinders well before installation, gap and orient the rings? |
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Snoopy1971
Samba Member
Joined: May 15, 2020
Posts: 311
Location: Parkville, Maryland
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| Posted: Mon Jul 21, 2025 11:52 am Post subject: Re: Overheating Help |
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| chrisflstf wrote: |
I assume you are sticking the candy thermometer in the dipstick hole?
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Yepper
| chrisflstf wrote: |
| Does it smell hot? |
I have no idea ... I guess Im not trained to smell hot .. You mean a smell of hot oil or a hot engine? Either way its nit something I noticed.
| chrisflstf wrote: |
| ICan you hold the dipstick? |
Yeah I know the rule of thumb about being able to hold the dipstick ... nope cant touch it. Have to pull it out with a rag.
| chrisflstf wrote: |
| IAny oil pressure gauge? |
No, dont have one
| chrisflstf wrote: |
| That first pic of oil change does not look good. Did you clean the cylinders well before installation, gap and orient the rings? |
Yes, yes, & yes
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