Thread: Over heated engine - NOW WHAT - your advice please

Before reply in detail to all you good guys the following

I compared the old 4.6 heads with the rebuild ex 3.9 heads I have waiting.
Differences:
Just one minor important accessory hole missing in the 3.9 ones, and the 3.9 has 4 extra head bolt holes on the outer side.

But what concerns me is the outer size of the exhaust ports:
3.9 : 20.5 x 31.2 mm or 639.6 mm2
4.6 : 23 x 33 mm or 759 mm2
a difference of 119.4 mm2
equals ... 15 % ...
The inlet dimensions of the header ports are a little larger as the 4.6 ports.

However this seems only close to the flange , more inward the dimensions appear more identical. How bad or not it this ?

See photos:

As far I know YES , Stainless steel headers they seem to be called.

The outer row of holes makes them really early heads, pre 3.9's.

Hi , I will answer , question in your post:

Have a look at Post #18 onwards Head Gasket Time... for pics


Definitely new cam.
With some judicious handling and moving stuff out of the way there's just enough room to slip a new cam in place without removing the engine. You need to be VERY careful not to score the bearings however.

The lobes in your photos are worn and seem chipped at the edges. New part number is ERR5250 ...about $190 from Karcraft. No point using a new cam if you don't put in new followers ERC4949 (about $10 ea). Should also put in new rockers.

OK NEW CAM I now can see why + NEW FOLLOWERS

I will bet also that your chain and sprocket wheels need replacing also. see pics above..that was only 140,000km!

WILL Know it once apart , did that on previous RR before, if half needed I will do that , and maybe do it anyway , any recommendation for the type of timing gear/chain type ?

The preload on the tappets/followers is critical. given that the pushrods are not adjustable you have only two real options: Drill out the holes in the head where the push rods go through to accept larger diameter adjustable pushrods... or... shim the rocker posts (all the same!!!) so that the average preload is within specs.

Are adjustable pushrods a 'save' option in the longterm : can they 'de-adjust' on their own , I understand that the preload is critical , BUT how to determine the accurate preload ?

These (preload) measurements are going to depend on the amount skimmed off the heads as well as the thickness of the headgasket. I used an Elring composite head gasket and tightened the heads only to 65-70 ft lbs in 4 stages. however in saying this, I also spent the money and bought a set of API head studs from the USA (Summit Racing) instead of TTY head bolts, though I am sure they would be OK if properly installed.

The new 3.9 heads have been skimmed off 0.5 mm , as they originally had tin gaskets and now will get composite gaskets.
I already have new bolts, from a mechanics point of view I can see that studs mount at the max depth in the engine block regardless tension , but is that really all that important ? Or is there an other reason why studs are really worth their money over bolts, a genuine practical reason I overlook ?

Have a look at PaulP38a 's webpage on his 'engine refresh' .

Great section !!

I bought the hydraulic lifters, solid steel rockers and a shim set from turner engineering in the UK. New chain and sprockets etc and camshaft plus top end overhaul gasket set (Elring) from Karcraft.

What makes the lifters and rockers from Turner better ?

Breaking in the camshaft has to be done properly... you can screw it up in the first 45 seconds you start the engione if you don't do it properly...forgive me if you already know this. I slathered the whole lot in assembly lube and filled the car with running-in oil I got from Repco (high phosphorus content) which U used for the first 1,000km then refilled with Magnatec 15-40.

Great learning !!

there's a lot of good advice on the turner engineering website.

sorry for the jumbled thoughts...yell out if you have a question

BIG THANKS FOR THE ELABORATE HELP
J.

Hi BEE UTEY , as you can see in my Reply to HOGES I will replace cam and followers , not sure yet about standard or adjustable tappets. Also it could be that what I think is a 3.9 head may be an older version. See my new post re. the heads.
I once had a 3.5 County which got a 4.6 block , but since the heads of the 3.5 were so good Graeme Coopers who did the job used those on that 4.6 . Would there be anything agains using those older style heads ... See the narrower exhaust ports in my post.

I bought the steel rockers because they are milled/machined from the one piece of iron. There's no pressed in cups as in alloy rockers. They are heavier than the alloy ones, however, for a low compression relatively low revving engine it's not significant in terms of performance/power loss.

The rocker set from Turners were guaranteed to be "matched". Since I bought the rockers, I also got the lifters because the price was 'right' and the postage cost was spread across all the bits which made it economic.

I bought the cam from Karcraft. It's stock standard aftermarket OEM spec from the original cam supplier. The local cost vs o'seas + postage was equivalent. Same for the gasket set.

I quickly came to realise that in doing this "upgrade" I could go through the catalogues and buy all the best "bits" ... matched heads/roller rockers/adjustable push rods/ Piper cam... first estimate was close to $5k..and it would still be a low compression agricultural donk ....
So in the end I went aftermarket OEM spec parts and it still cost about $2k all up.While I was on the job I replaced the cam sensor and also the water pump, coil blocks and ignition leads (preventative maintenance).

Preload: see Adjustable push rods / roller rockers on 4.6 V8? .. post #8, in regard to measuring preload. Frankly, had I been more knowledeable I'd have gone the adjustable rocker route... next time!

Please used the studs, the difference is in what you've found in taking it apart. TTY bolts are something that the person with the original concept when had should have been beaten until they forgot all about it.

I've run tests on both Toyota (UZ) and LR (4.0/4.6 blocks) TTY bolts and the location of the stretch in the bolt length, the amount of stretch and most importantly (I feel) their lack of ability to hold tension, why you find them loose on dis-assembly. For example, I tensioned a test set and left overnight and 70+% were found 24hrs later to be under tensioned.

Originally Posted by JaapRoskam

Hi BEE UTEY , as you can see in my Reply to HOGES I will replace cam and followers , not sure yet about standard or adjustable tappets. Also it could be that what I think is a 3.9 head may be an older version. See my new post re. the heads.
I once had a 3.5 County which got a 4.6 block , but since the heads of the 3.5 were so good Graeme Coopers who did the job used those on that 4.6 . Would there be anything agains using those older style heads ... See the narrower exhaust ports in my post.

Couldn't you get your heads ported?