desmato

I have a 2010 MDX and had to replace my engine @151k due to a spun bearing from oil consumption. (1 qt in 540 miles and dealer/honda washed their hands)

Front head was caked in burnt oil and one lobe started to come apart. Rear head is gorgeous.

Now for the new engine. Long story but It tossed a timing belt 6300 miles after install (all new parts, crank drive gear for belt broke...) had to remove heads and have 4 valves replaced. Front head on newer engine showing same discoloration though not as severe (69k miles vs 151k) and during assembly I noticed a possible screwup by Honda that could be part of the issue with the galling and burnt oil issues (aside from the PCV being on this head).

As seen in the pics, the rocker saddle locating dowel on the front head is a solid pin whereas the rear head uses a hollow dowel. From what I can tell, this is where the rocker shafts are supplied with oil. If this is the case, why would the front head have the oil supply blocked with a solid dowel ? Both of my 3.7 engines were built this way.

I wonder if it would be a bad idea to put a hollow dowel in the front head and/or if it supposed to have a hollow dowel ? I need to finish this repair in the next few days and am at a standstill until I get answers.

Pics for ref.

Solid dowel on front head


Hollow dowel on rear head

Wiped lobe cyl #4 exh.






Burnt oil in front head and solid dowel in oil supply hole

Skirmich

Just FYI.. Head discoloration has nothing to do with "Burnt Oil" or the Burning oil issues, It is mainly a side effect of how the PCV System Works in the J-Series.. All J-Series show this kind of color discrepancy.

My 2002 J32A2:


My 2007 MDX:

Skirmich

As for the damaged heads well it can always be attributed to low oil... It happens a lot on the +2010 MDX due to the oil consumption issues that plague those years J37s

desmato

So no comment on the rocker shaft oiling port and the solid vs hollow pin that this thread is about ?

I've been a mechanic for 32 years and worked on 100s of engines, rarely have I seen a condition where one head is caked with deposits and the other is pristine. Usually they both are and it's from lack of maintenance, poor design (GM 229 V6) or junk oil. I dont buy the "pcv in that head" reason that everyone is settling on, especially on a Honda. Most engines have the pcv in one head and when do you see caked up oil in them and not the other ? As for oil consumption, yeah that's a thing but doesn't have any connection to the oil deposits and build up.

Camshaft galling is a common issue on the J37. I've not heard of a J32 or J35 with the same rate of occurrence. Most know that the J37 has issues, like rings and cams, but proper root cause analysis goes way beyond armchair diagnostics.

Way to easy for people to regurgitate what they are told/hear

Skirmich

Well I haven´t being a mechanic for 32 years so I could not comment on that I guess.

desmato

Wasn't trying to be a jerk, please don't take it that way. I know the PCV heads get a stain effect but this is way beyond that. The old engine was drinking oil at a rate of ~ 1+qt / 500 miles and if more was being pulled through the PCV that normal, I could see a bit more oil staining in that head but the caked on deposits are extreme in my opinion and experience. Truth be told, it was due this summer for a full service since the last was @ 82k according to the dealer when purchased used. But, a spun bearing led me down the path of a new/used engine. For all I know, all the oil was being consumed through the PCV and not the rings. Never got the chance to to find out

I pulled the parts diagrams for those dowels and each head uses a different part #, though I can't find decent pics to really tell. I also talked to the local dealer and I got a lot of shoulder shrugging. So, I decided to put the hollow dowel in the front head and see if there's any effect, good or bad. Easy-ish enough to remedy, if needed, though I can't reason how more/better oiling is a bad thing especially since the rear head, which is the same valve train, has it.

Todd

csmeance

2010-2013 MDX have VTEC on intake and exhaust assembly. It could be there to prevent oil pressure loss but I could be very wrong. Your best bet is to check the Service Manual on re-assembly of the heads to show what pin goes where, and as well the oiling system. I only have a 2007 manual which does not have the updated info for the dual VTEC system. Acura also has different sized dowels for front front and rear head so it'd be worth googling the part #'s for pictures/info of what goes where. It could be a misplaced dowel from when the valves were done. There's a few guys on Rv6 who play with J37's who might know about this; also I'd direct you to ask on the facebook J-series page which has a TON of knowledgeable folks. I'd be more than happy to ask your question there if you'd like!

desmato

Our 2010 MDX only has the VTEC on the intake. Engine is together and I have noticed no difference in performance etc. with the hollow pin in the front head. Parts diagrams show different #s for each pin but no real pics. Service manual is still lost in the mail.

csmeance

2010 uses J37A2 which has dual vtec, look at the cam:
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desmato

Did you look at the pics ????? Intake only

desmato

1 month & 2k miles. So far, so good & no noticeable difference in the VTEC operation. 4k rpm and it wakes right up like before. I'm going to pull the valve cover in the spring to give it a once over and see if there is any change in the oil deposits.

Also, I want to offer up the old engine (spun rod bearing) for sale but the forum will not let me post. (It's been way over 15 days and 5 posts) Anyone interested in it ? otherwise I'm going to strip it down and off to the scrap yard.

Todd