T4 Tear Down / Rebuild in Jax FL

[analogtherapy]

Well I'm finally able to bring this thread to a close. The engine is in, and I just timed/tuned it up yesterday, and I should be going for a few short test drives a bit later today.

A massive thank you to everyone who helped along the way (whether directly, by answering my questions, or indirectly, by sharing what they know in their own posts). Thank you Lo Cash John, Piledriver, Clatter, Ray Greenwood and everyone else who contributed!

[BBvideo=560,315]https://www.youtube.com/watch?v=HkE6HKrfrXQ[/BBvideo]

[Gnasha]

Hello, let me the first to congratulate you on a great build, a job well done. I have followed every stage with interest and admiration for you tenacity and attention to detail.

I hope you enjoy your hard work for many years to come.

Gnasha

[Clatter]

Nice!

Wondered how this was going...

Have plenty of patience for any shakedown niggles, there's always at least a few.

Tune it with a wideband on the highway,
Give it plenty of oil changes, valve adjustment/checks, and miles!

[analogtherapy]

Hello, let me the first to congratulate you on a great build, a job well done. I have followed every stage with interest and admiration for you tenacity and attention to detail.

I hope you enjoy your hard work for many years to come.

Gnasha

Thanks Gnasha, that's very kind of you to say and I really appreciate it!

Nice!

Wondered how this was going...

Have plenty of patience for any shakedown niggles, there's always at least a few.

Tune it with a wideband on the highway,
Give it plenty of oil changes, valve adjustment/checks, and miles!

Thank you Clatter sir! Your cheap build thread was a major factor in me even considering this rebuild.

Currently I'm struggling through carb balancing woes (everything sounds incredible in the driveway, but pops thru the carbs and struggles under acceleration when driving). I'm going to tackle them again this Saturday, but may be starting a new thread if I can't figure it out.

So close...

[Clatter]

Hi,

That was your thread about CHT you posted on the Samba, right?
Sorry it got out derailed.. Happens there a lot lately.

If you post up your running temp situation here,
You will be likely to get some good info.

Do you have a wideband?

[analogtherapy]

Hi,

That was your thread about CHT you posted on the Samba, right?
Sorry it got out derailed.. Happens there a lot lately.

If you post up your running temp situation here,
You will be likely to get some good info.

Do you have a wideband?

Hey Clatter,

Yea. I enjoy TheSamba but good info seems to be hit or miss lately.

Concerning the issue mentioned in my previous post, I started slowly increasing my idle jets. Started with 50, 52.5, 55, and lastly 57.5 (which I'm currently still using). Right now, the bus is very drive-able, except for a narrow flat spot...maybe somewhere around 2200 rpm? When I hit this flat spot, the bus seems to lose power/hesitates, and if I continue to hold that position, it will eventually let out a 'pop' through the carbs. However, if I change the position of the accelerator...whether I let off a little, or push a bit more, it balances out and I can cruise like that all day. But, if I get a red light...stop...start again, and hit that narrow spot...it happens again. I'd like to get rid of it, but I could honestly live with it.

I wish I had a wideband, so I could really know where I'm lean/rich. But I don't.



The CHT issue might have just been me being overly sensitive, but here's the details for anyone else to chime in with.

From TheSamba:

*********

I just completed my first complete T4 2.0 rebuild a few weeks ago, and today was the first day I drove it on the highway. I drove no faster than 60-65 mph, but my CHT for #3 hit 425 F and really freaked me out. As soon as that happened, I turned around and headed back home. I was on the highway for maybe 10-15 min total. I stopped to pick up some lunch, got back in and started her up. My oil pressure light stayed on noticeably longer than normal (it usually goes out right after startup and a blip or two of the throttle). This time it stayed on...still on...one or two pushes on the throttle...still on....flickered for a few seconds, then finally went out. Right now I'm running Brad Penn SAE 30 Break-in oil.

Prior to this highway test, I'd only been driving neighborhood streets, and my max CHT was about 351.

My questions are:

What CHT's should I expect to see during break in? Was/is sustained highway speeds too much too soon?

Was the oil light issue a result of oil becoming too thin/too hot, and therefore loss of pressure occurred?

Addtl info (may or may not be relevant): GE engine running dual Weber 40 IDF's. Currently running 55 jets, but running slightly lean. Will be switching to 57.5 jets very soon. Timing set @ 28 BTDC max advance. Valve adjustment set @ .002, running chromoly push rods w/solid lifters.

Outside temp today was about 74 F.

Thanks!

*********

So, since that post I did change to 57.5 idle jets, and I readjusted my valves to .004. I have not taken the bus back out on the highway yet, but have gone for a few cruises at slightly lower speeds (generally maxing out at 55 mph) and temps never hit over 400.

[wreck]

400F is supposed to be the highest safe limit but I think it's still too high , Jabaru a company that make 4 cylinder aircraft engines list 180c or 356F as the safe upper limit for continuous use . That is what I go by now .
Try bumping the timing up to in 2 degree jumps .I know a few people that can run up to 36 degrees . I run at 32 degrees , every engine is slightly different . I would also get an oil temp and pressure gauge , very hard to know what it happening with the oil without that info .

[Gnasha]

I'm new to ACVW's so this is a newbie's opinion.

A conventional motor oil will with stand temperatures of up to 250F 122C, but starts breaking down over 275 deg 135C. the prudent advice is to operate between temperatures 230 and 260F 110C 126 C. On the other hand I wouldn't like to operate lower than 200F-deg 93C oil temps.
Alternatively a full-synthetic oil will withstand sump temperatures in excess of 300F deg 148C, I suppose this is what you're referring to above?

[wreck]

the temperatures I was referring to are cylinder head temperatures measured at the spark plug boss . Oil temperature is a contentious subject and causes endless debate .In my experience and advise from a professional VW air-cooled engine builder I like to keep the oil below 100C.(Both my cars have thermostat oil control at 80C and enough cooling to keep it there .I don't get condensation in my oil )
Yes the oil can go a lot hotter and not break down but you also have to take into account the alloy case is also getting hotter and clearances are expanding .So lifter bores and main bearings saddles /cam bearing saddles etc are opening up .

[Gnasha]

I’ve misread the detail, my apologies. On the subject of head temperatures. Would you advocate the head temperature sensor under the spark plug or the specific threaded hole on the 3 and4 head.

[wreck]

the best place is under the plug because that is where most data on temperatures are from ,which is difficult on a Type 4 , I pinned the thermocouples against the plug bosses and used deacon /JB weld to build up over them .

[Gnasha]

I would agree, the temperature from around the plug will be higher at normal running temperatures than the factory specified area IMO. This would give you additional reactionary time to respond. I've seen people fit the sensor under the plug and grind a slot to allow the wire to sit flat.

What is an acceptable head temp for a type 4? 350F -375F. (176C - 190C) is there a corresponding oil temperature?

[analogtherapy]

I appreciate the feedback gents.

It seems that opinions vary widely of acceptable head temps. I've looked for an official number from VW, but have yet to find one. I guess it just varies (based on climate, engine health, and age)? I've read several opinions that since this is a new engine (still under 500 miles since build) that increased head temps are normal and that after about 1000 miles temps will start to decrease. I don't know if that is true or not, but it makes sense to me (tighter tolerances, higher friction).

I took the bus out for a drive yesterday evening and stayed in the range of 45 - 55 mph for the majority of the time. Head temp stayed around 350F-/+. I took it out on the highway for a short while (60 - 65 mph) and temps never got higher than 385F. They might have, if I drove longer, but it did seem to stabilize around that temp. Granted...it was about 50F outside last night, so colder than my initial tests. I don't know how much of an influence that has or not.

Also, I switched to 20W-50 (PennGrade 1), and never once had an issue with the oil light/oil pressure during the drive.

[wreck]

I've noticed on my 2 cars that head temps will get to temperature pretty quick ,say 10 minutes driving then they will change quickly up and down depending on revs and engine load . In my case with my custom shroud Cali style up right conversion ,the temps can run from around 200f at very light load at say 4500 rpm (high fan speed) to 270 F with load on the engine at lower revs .Then at idle I see around 250F. My temps are a lot lower then what you'd see in a bus because this engine is a 2600cc in a Ghia so not working hard at all. ambient temps for those readings would be around low 80F range .

Some thing I would recommend on a bus in a hot climate is the push rod sprinkler mod ,a small hole drilled at the end of the push rod that sprays oil on the cylinder head and valve springs as it rotates around, It is a simple mod that works . It will increase oil temp but that is easy fixed with Mocal oil filter sandwich plate with thermostat and remote cooler or coolers .
A good friend that is a professional air cooled engine builder started fitting oil sprays to the heads to combat only getting 50 to 60k miles from valve guides , he noticed the big rise in oil temp straight away and fitted another cooler (4 in total now) correctly deducing the oil was also pulling heat from the heads. After a year or two he also noticed no more dropped seats .He works his bus harder than anyone I've ever seen and still gets big miles from his engines ,his last engine was an under bench scraps throw together but still did over 125000miles and the heads had 200000m on them before he pulled it because it was getting a bit tired , his secret is simple , keep it cool ,his oil temps would rarely get over 180C if ever.
.

John's loaded .jpg

[Gnasha]

love the photo, love the weather, and the bus looks awesome too.

I'm in the process of the JC conversion, I have the manual and two type 4 engines (GE and GD). Although I'd like to improve there potential, Webers, mild cam, bigger valves etc I wont be going to increase displacement at this stage, (2.6 would be the death of me). The finished product will be going into a 73 Ghia.

I'm very interested in the push rod sprays, do you have any photos? My research tells me the type 4 cooler in the T1 fan shroud has been known to run a lot cooler and some people have reverted to the T1 cooler or changed the thermostat to the 90deg type 4 spec.

I had thought about using your method of the sandwich plate and the incorporated thermostat, but what operates your flaps?

PS in the UK we dream of weather like that