Go Back   986 Forum - for Porsche Boxster & Cayman Owners > Porsche Boxster & Cayman Forums > Performance and Technical chat

Reply
 
LinkBack Thread Tools Display Modes
Old 05-24-2016, 03:53 PM   #1
Rennzenn
 
j.fro's Avatar
 
Join Date: Feb 2005
Location: Virginia
Posts: 1,355
Garage
Question for engine experts

I've heard that the heads on 99-01 3.4L engines and 00-01 3.2L engines are the same...
My 99 996 C4 has oil in the coolant, so I'm guessing cracked head. My plan is to swap in a used 3.4.
So, if the bottom end on my old 3.4 is good, can I put my Boxster S 3.2 heads on and get some added displacement?? (Hopefully a good port/polish is in the budget).
__________________
Rennzenn
Jfro@rennzenn.com
j.fro is offline   Reply With Quote
Old 05-24-2016, 04:16 PM   #2
Registered User
 
Join Date: Dec 2009
Location: Orange County, CA
Posts: 1,227
Quote:
Originally Posted by j.fro View Post
I've heard that the heads on 99-01 3.4L engines and 00-01 3.2L engines are the same...
My 99 996 C4 has oil in the coolant, so I'm guessing cracked head. My plan is to swap in a used 3.4.
So, if the bottom end on my old 3.4 is good, can I put my Boxster S 3.2 heads on and get some added displacement?? (Hopefully a good port/polish is in the budget).
J.fro, Have you checked the heat exchanger?
Gilles is offline   Reply With Quote
Old 05-24-2016, 05:05 PM   #3
Registered User
 
Join Date: Dec 2014
Location: Pasadena
Posts: 252
Oil in coolant = not nessecarily cracked head. Could just be blown Head Gasket.
Lapister is offline   Reply With Quote
Old 05-24-2016, 05:41 PM   #4
Certified Boxster Addict
 
Join Date: Nov 2010
Location: Los Angeles
Posts: 7,421
Cracked heads and failed head gaskets are actually fairly rare and are usually the result of severe overheating.

If the everything was fine until you found intermix, then I agree with Gilles and suggest checking the oil cooler as they are known to fail with this result.
__________________
1999 996 C2 - sold - bought back - sold for more
1997 Spec Boxster BSR #254
1979 911 SC
POC Licensed DE/TT Instructor
thstone is offline   Reply With Quote
Old 05-24-2016, 05:47 PM   #5
Registered User
 
Join Date: Jan 2016
Location: Western Australia
Posts: 91
oil cooler is one common cause, they use coolant to oil sandwich cooler
rusty69911 is offline   Reply With Quote
Old 05-25-2016, 12:27 AM   #6
Registered User
 
Join Date: Jun 2014
Location: LB, Germany
Posts: 1,322
Hello,

cylinder heads. From the part number the heads seems to be different – so there might be differences, so you should check that in very detail (even if the 986 parts number says 996 in the beginning):
986S - bank 1: 996 104 001 09
986S - bank 2: 996 104 002 09
996 - bank 1: 996 104 003 05
996 - bank 1: 996 104 004 05

Also the prior part numbers don't match.

It's pretty unusual that cylinder head gaskets break in this engines. Mostly it's a cracked cylinder – open deck design. If you have access to an endoscope camera you can check it with pulled sparks.

The 996 doesn't have a combined water / oil cooler. The oil cooler system is completely separated.

Regards, Markus

Last edited by Smallblock454; 05-25-2016 at 12:34 AM.
Smallblock454 is offline   Reply With Quote
Old 05-25-2016, 03:50 AM   #7
Registered User
 
itsnotanova's Avatar
 
Join Date: Jul 2013
Location: Bastrop, Tx
Posts: 2,184
I've heard the 3.2 and 3.4 use the same heads from a few different people.
__________________
Woody
itsnotanova is offline   Reply With Quote
Old 05-25-2016, 08:15 AM   #8
Registered User
 
Join Date: Feb 2005
Location: It's a kind of magic.....
Posts: 5,095
Quote:
Originally Posted by Smallblock454 View Post


The 996 doesn't have a combined water / oil cooler. The oil cooler system is completely separated.
Sorry, but every 996 ever made uses an oil to water heat exchanger/cooler, just like the Boxster, because the 996 uses the same basic engine layout.
__________________
Anything really new is invented only in one’s youth. Later, one becomes more experienced, more famous – and more stupid.” - Albert Einstein
JFP in PA is offline   Reply With Quote
Old 05-25-2016, 08:59 AM   #9
Rennzenn
 
j.fro's Avatar
 
Join Date: Feb 2005
Location: Virginia
Posts: 1,355
Garage
JFP, do you have insight regarding 3.2 & 3.4 heads?
I've sent an oil sample to Blackstone for analysis... we'll see what they have to say.
I found the oil in coolant (just a bit of Choco on the top of the coolant in the reservoir) as I inspected a couple of days after making a 400 mile trip from VA to SC. I was running Dash Command for the duration of the trip, just watching data. As I got into traffic, coolant temps climbed from a highway temp of around 180 to a max of 223. I noticed that I could smell coolant. I turned on the AC to get the fans going, and that bought temps down to around 210.
It'd be nice if it's just the heat exchanger, but I'm still guessing heads. If the bottom end is still good and the 3.2 heads will work, then the 996 gets a salvage motor and the 986 gets a hot rodded 3.4. And I'll be functionally broke for a good while.
__________________
Rennzenn
Jfro@rennzenn.com
j.fro is offline   Reply With Quote
Old 05-25-2016, 09:23 AM   #10
Registered User
 
Join Date: Feb 2005
Location: It's a kind of magic.....
Posts: 5,095
If you think you have a cylinder head issue, try running a leak down and/or bore scoping the suspect.

You can interchange 3.2 and 3.4 cylinder heads within certain bounds and caveats: Both engines need to be 5 chain designs to allow this to happen as there were no 3 chain 3.4 engines. The 3.2 heads will increase the compression ratio a small amount due to their very slightly smaller chambers, and both use same camshafts. There is also some difference in the intake arrangement.

3.6 heads are not usable because of the VarioCam+ .
__________________
Anything really new is invented only in one’s youth. Later, one becomes more experienced, more famous – and more stupid.” - Albert Einstein

Last edited by JFP in PA; 05-25-2016 at 09:29 AM.
JFP in PA is offline   Reply With Quote
Old 05-25-2016, 10:24 AM   #11
Registered User
 
Join Date: Jun 2014
Location: LB, Germany
Posts: 1,322
Quote:
Originally Posted by JFP in PA View Post
Sorry, but every 996 ever made uses an oil to water heat exchanger/cooler, just like the Boxster, because the 996 uses the same basic engine layout.
Ups, sorry, i've meant something different. For example Mercedes cars have a combined water/oil cooler in front of the car. This is one cooler element that has 2 chambers for both fluids. The front coolers of the 986 / 996 are separated.

Regards, Markus
Smallblock454 is offline   Reply With Quote
Old 05-25-2016, 12:33 PM   #12
Project Addicted
 
jcslocum's Avatar
 
Join Date: Aug 2015
Location: Eastern Shore, MD
Posts: 623
We had a failed oil cooler on our 2.7 when doing a refurb. It's easy to pull off and test with an air gun and 1 rubber plug. Bubbles showed up instantly and we knew we had the culprit. This made the fix simple but getting the oil out of the system was a bear!!!
__________________
______
Jon
1966 912, 1976 911
1986 944, 2000 Boxster
jcslocum is offline   Reply With Quote
Old 05-25-2016, 04:12 PM   #13
Registered User
 
BYprodriver's Avatar
 
Join Date: Oct 2008
Location: O.C. CA
Posts: 3,188
Garage
Quote:
Originally Posted by JFP in PA View Post
If you think you have a cylinder head issue, try running a leak down and/or bore scoping the suspect.

You can interchange 3.2 and 3.4 cylinder heads within certain bounds and caveats: Both engines need to be 5 chain designs to allow this to happen as there were no 3 chain 3.4 engines. The 3.2 heads will increase the compression ratio a small amount due to their very slightly smaller chambers, and both use same camshafts. There is also some difference in the intake arrangement.

3.6 heads are not usable because of the VarioCam+ .
The heads are the same casting including the bolt hole bosses. Depending on application (3.4 or 3.2) holes are drilled & taped for bolt on accessories & combustion chambers are finished with 3cc's less volume for the 3.2L to maintain compression ratio Valvetrain is the same.
__________________
2000 S Speed YellowLN 3.6L cylinders & pistons, triple row IMSB upgrade, R&R connecting rods, billet tensioner paddle,oilpump driveshaft.Heads rebuilt by F6I with new valves & springs.Cayman airbox & MAF housing, 996 intake plenum & 75mm T/B. NHP sport converters &Dansk muffler

Last edited by BYprodriver; 06-18-2016 at 07:01 AM. Reason: correction
BYprodriver is offline   Reply With Quote
Old 05-25-2016, 04:59 PM   #14
Registered User
 
flaps10's Avatar
 
Join Date: Jul 2014
Location: Tacoma
Posts: 430
^This. And I think the 996 heads will have the other holes for the intake manifolds.

I'm not an engine expert but I play one on the internet. There was a comment above that the heads don't crack often. Actually cracks around the valve seats and plug hole aren't that uncommon. My train wreck had one cylinder head that had been previously welded, and I've seen plenty of photo evidence and statements to come to the conclusion that it shouldn't be discounted.

As JFP (who is an engine expert) mentions, do a leakdown.
flaps10 is offline   Reply With Quote
Old 05-26-2016, 02:27 AM   #15
Rennzenn
 
j.fro's Avatar
 
Join Date: Feb 2005
Location: Virginia
Posts: 1,355
Garage
Thanks for all the info.
Never done a leak down, but I've read about the process. What should I be looking for?
__________________
Rennzenn
Jfro@rennzenn.com
j.fro is offline   Reply With Quote
Old 06-16-2016, 07:34 PM   #16
Registered User
 
madmodz's Avatar
 
Join Date: Jul 2012
Location: Scottsdale, AZ
Posts: 174
I thought I blew my head too. It happened to be the oil cooler. I replaced it with the bigger S model
madmodz is offline   Reply With Quote
Old 06-16-2016, 09:25 PM   #17
Registered User
 
Join Date: Jun 2014
Location: LB, Germany
Posts: 1,322
Quote:
Originally Posted by j.fro View Post
Thanks for all the info.
Never done a leak down, but I've read about the process. What should I be looking for?
Hello,

i would recommend a simple compression test of every cylinder first. So you'll see if there is a cylinder that is out of specs, which will be a good indicator.

If you have a endoscope camera you can inspect the cylinders. But it is difficult to inspect the heads with a cheap one, because for that you need to direct the camera into the direction from where you put in the camera. Also you need to interpret what you see there.

The combines oil & water cooler is on top of the engine. There are round rubber seals below the cooler. Sometimes they fail. So if it is oily or wet there, this can be an indicator that a seal failed. Also the cooler can fail internally.

Regards, Markus
Smallblock454 is offline   Reply With Quote
Old 06-18-2016, 06:59 AM   #18
Registered User
 
BYprodriver's Avatar
 
Join Date: Oct 2008
Location: O.C. CA
Posts: 3,188
Garage
Quote:
Originally Posted by BYprodriver View Post
The heads are the same casting including the bolt hole bosses. Depending on application (3.4 or 3.2) holes are drilled & taped for bolt on accessories & combustion chambers are finished with 3cc's less volume for the 3.2L to maintain compression ratio with smaller bore size. Valvetrain is the same.

(corrected post from original text)
__________________
2000 S Speed YellowLN 3.6L cylinders & pistons, triple row IMSB upgrade, R&R connecting rods, billet tensioner paddle,oilpump driveshaft.Heads rebuilt by F6I with new valves & springs.Cayman airbox & MAF housing, 996 intake plenum & 75mm T/B. NHP sport converters &Dansk muffler
BYprodriver is offline   Reply With Quote
Reply


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On




All times are GMT -8. The time now is 03:12 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
Content Relevant URLs by vBSEO 3.6.0
Copyright 2018 Pelican Parts, LLC - Posts may be archived for display on the Pelican Parts Website -    DMCA Registered Agent Contact Page