Project 24

[murrayis]

Yea when we got the car home, we started it to have a listen while it was quiet and the noise definetly sounded like it was high up in the engine.

I converted it to a Solid lifter setup so nothing should fail in there... Only things I can think of is a shims come off or a valve guys failed or a bent valve.. its jsut strange seeing there was ear to no blow by out the cam breathers then on the third run the loss of 20kw and alot of blow by so air was mixing with oil somewhere...

I'll update it tomorrow once we pull the head of in the morning. Fingers crossed its nothing major!

[murrayis]

Well we went at it this mornign to remove the head, but in the process of lining up the cams so we could get at the head stud nuts we noticed it was taking alot of effort to sping the cam shafts so we decided to remove the cams to check it out...

Intake cam was first... no major marks all the usual little blemishes some the new cams running in. Exhaust cam was next removed all the caps and when with lifted the front most cap we found this!

We lifted the Cam out no major marks on the cam thank god! and the bottom side of the head we found this

We are looking at maybe taking the head off and getting it line bored after we take too it with some 1000+ wet&dry to clean of the bores to see if there is any deeper damage.

This had both of us scratching our head as to what has caused this!

If anyone has seen this before please let me know etc. All the caps were torqued down to manafactuer specs in correct order etc.

Cheers

Cameron

Edited January 11, 2009 by murrayis

[CEF11E]

looks like there was no oil supply. it looks like those scores are dry as a bone. that really is some nasty stuff right there. perhaps the oil galler is fouled up or got something lodged in it. or perhaps the head gasket you are usinng does not have provision for oil supply in the gallery between the head and the block.

could be worse! that dosent explain your blow by tho. did you stagger the gaps in the rings when they were put in?

[murrayis]

  CEF11E said:

looks like there was no oil supply. it looks like those scores are dry as a bone. that really is some nasty stuff right there. perhaps the oil galler is fouled up or got something lodged in it. or perhaps the head gasket you are usinng does not have provision for oil supply in the gallery between the head and the block.

could be worse! that dosent explain your blow by tho. did you stagger the gaps in the rings when they were put in?

I am not sure about the gaps in the rings as I didn't do that part of the build, but I am sure they were.

When we pulled the cam there was oil on the face which wasin contact with the damage, and I pushed a good 30cm of plastic tube down into the oil feed hole to check to see if it was blocked and didnt see any problems.

I am stumped to would have caused this my thinking was no oil supply, The head gasket is a RB20DET TOMEI 83mm unit and from memory when i Lined it up with the standard nissan gasket to check the oil hoels etc they were both spot on the money.

Cameron

Edited January 11, 2009 by murrayis

[dangerman4]

seeing as the intake cam is fine i would assume there is something inside the head blocking the oil gallery to the exhaust cam.

if the head is off stick some compressed air into where the oil feeds into the head and note the air coming out of the cam bearing holes on both sides.

or if the heads still on the car with the cams removed crank it over and watch how much oil comes out of the oil holes at each bearing.

if the cams are removed all your valves will be shut so no need to worry about pistons hitting anything, just remove your plugs and crank it.

Edited January 11, 2009 by dangerman4

[murrayis]

Thanks for the sujestion, oil galleries are clearminiture cameras are awsome lol I fed some oil into the hole in the damaged area and removed a lifter and looked up the oil gallery with the camera and the oils came straight out.

I think I know what caused this failure. I notised the cam belt was tight the other week after setting it correctly so i adjustened it again and this mornign when we took the belt off it was really tight again, my thinking is it was putting too much downward pressure on the front of the cam at too higher rpm's 7000+rpm causing the cam to dig in and deposit what it dug out on the cap as you can see.

Now if this is the case I need to work out why the tension on the belt keeps changing. Any Idea if this could be possible?

My reasoning behind this is... Seeing its running in oil with the added downforce on the front of the cam the oil couldnt handle the pressure making it usless thus not providing sufficiant lubrication.

Edited January 11, 2009 by murrayis

[dangerman4]

i highly doubt that would be a possible cause.

you would need a hell of a lot of tension on the belt to cause an issue.

the fact that the belt is changing tension is a bit of a concern.

what brand of belt?

new tensioner and idler?

new bolts for the tensioner and idler?

[murrayis]

New Gates belt, near new idler and tensioner were form my last engine and only did 5000k'swith them not new bolts but they will be I am picking up new Tensioner and Idler this afternoon and tossing up the idea of a new timing belt also.

Do you recommend a new stud and nut or replace them both with HT bolts?

[1400r]

huddy's got his 2.4 for sale now

trust me when you get it running right it will be reliable as

[murrayis]

thanks for the positive words

I Just finished cleaning up the cam bucket

Need opinions on it.

Cameron.

Edited January 12, 2009 by murrayis

[dangerman4]

yep replace the belt with a genuine nissan one.

and i would certainly be removing the head and getting it line bored to suit the tollerances of your cams.

what's your oil pump like?

[Dale FZ1]

Get the camshaft checked for runout especially on that journal.

[murrayis]

  dangerman4 said:

yep replace the belt with a genuine nissan one.

and i would certainly be removing the head and getting it line bored to suit the tollerances of your cams.

what's your oil pump like?

Have a new Gates belt that should arrive tomorrow. Oil pump is a band new Nissan Rb26 Item.

  Dale FZ1 said:

Get the camshaft checked for runout especially on that journal.

Not sure I know what you mean by runout? and if its what I think it is would you know anyone in Brisbane who would perform this?

Cheers

Cameron

[Dale FZ1]

Get the shaft checked that it is straight and true. If there is a slight bend, you have trouble. If your oil gallery is clean + clear of obstruction then you'd be looking for something else to have caused the contact between journal and cap.

Any reputable cam specialist or reputable engineering shop could do the check for minimal $$ and before you go doing anything with the head that may not need doing.

[murrayis]

ok thanks, I will give Briant engineering a call tomorrow.

hopefully the head wont need any work i only cleaned up the crap that was bashed into the surface to give you an idea i used 1200 wet and dry for about 5 mins to get it back to that last picture.

Cameron

[murrayis]

Hi,

I just dropped the cams off to the engineering shop $20 to polish them up and check the runout.

I said to him the cam started to bind up and his first reaction was "you using one of those blue gates belts?" he said hes seen heaps of these that when the head warms up and expands slightly the belt doesnt stretch and pulls the cam into the bucket causing too much heat and binds up, a few times has snapped the cam shafts.

Cameron.

Edited January 12, 2009 by murrayis

[Swiper the Fox]

  murrayis said:

Hi,

I just dropped the cams off to the engineering shop $20 to polish them up and check the runout.

I said to him the cam started to bind up and his first reaction was "you using one of those blue gates belts?" he said hes seen heaps of these that when the head warms up and expands slightly the belt doesnt stretch and pulls the cam into the bucket causing too much heat and binds up, a few times has snapped the cam shafts.

Cameron.

Or snaps the idler bearing bolt.

[murrayis]

  DiRTgarage said:

Or snaps the idler bearing bolt.

Yep not taking the risk, thats why I am replacing the idler. tensioner and belt, also thinking of changing form a stud to bolt arrangment for the two.

Have you seen this sort of thing before Mr. Dirt?

Cameron.

[dangerman4]

genuine nissan belt FTW

[Swiper the Fox]

  murrayis said:

Yep not taking the risk, thats why I am replacing the idler. tensioner and belt, also thinking of changing form a stud to bolt arrangment for the two.

Have you seen this sort of thing before Mr. Dirt?

Cameron.

Have looked into making up studs for both using hi-tensile material but have gone back to replacing all the hardware with genuine items for all builds (about $30 to replace everything including washers etc). The issue of lack of flex in high tensile stuff could result in cracking the blocks across to the welsh plug gallery on the front of the engine.