4k/5k head (Thermostat housing compatibility)

[Thomas Dillon]

Hi team, 

Currently in the process of rebuilding a wee kp for summertime skids & coffee cruising. 
 

Bought the kp and have come to realise it’s got a dished piston bottom end and what I believe to be a 5k head and have confirm this with the previous owner but it’s all “apparently”. The head has got the two knobs under each spark tube at both ends. 
 

Anyway, I’ve turfed the facto radiator and electric fan and have gone for the Fenix ke70 ally rad/fan shroud kit for maximum coolage when abusing it over the takaka hill. 
 

Question being, are the entire top & bottom thermostat housings compatible across the range of 2k-5k heads? 
 

My current thermostat housing outlet is shooting off towards the right hand side of the bay if you’re looking at the motor. The Fenix top tank outlet is on the left hand side. 
 

Option 1: I run a 180 degree rad hose off the current set up, through a length of stainless and into the radiator. (Not the end of the world). 
 

Option 2: we tidy things up and put one of the other thermostat housings on that shoot the other way. 
 

basically just wanting to know if they bolt to the head all the same. 

Really appreciate ya help in advance, 

Cheers fellars 

 

[Banjo]

Frankly, after all the K Series engines, I've seen on the net, & in real life; I can't remember ever seeing one with the top outlet spout, pointing towards the RHS.  All the ones I've seen point towards the LHS; as on my 4K test bed engine below.

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The head has got the two knobs under each spark tube at both ends. 

That is definitely a 5K head.  It was the only K Series head with two "knobs" in the casting under the end spark plug sockets, I'm led to believe.

The crankshaft front pulley, looks as if it is 5K. The two sandwiched pulleies were common, as the 5K engines were used in Toyota forklifts & the like, & drove various pumps/compressors etc, off the additional pulley.

However, the front camshaft sprocket cover, does not look 5K, as the timing chain marks are in the wrong place.

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Option 2: we tidy things up and put one of the other thermostat housings on that shoot the other way. 

Definitely get a top hose outlet, that points in the opposite direction. Will look so much better, in the engine bay.

As far as I know, the bottom thermostat housings are all the same, as are the water pumps.

Someone correct me, if I'm wrong.

Have You had this engine running ?  If the block is a 5K, then T.D.C. No 1, will be a bit out, if You line up the crank pulley timing nick, with the timing marks on the camshaft sprocket case.

I covered this topic, in a post years ago, when I fitted a  5K crankshaft pully, onto a 4K engine.

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https://www.rollaclub.com/board/topic/83250-4k-efi-test-rig-iac-valve/page/2/#comment-733591

Cheers Banjo

Edited 12 hours ago by Banjo

[altezzaclub]

Why don't you just turn the outlet around 180deg? Aren't they symmetrical?

[Banjo]

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Why don't you just turn the outlet around 180deg? Aren't they symmetrical?

In theory, they visibly look like they are, (says He scratching his head), I'll have to go out ito the garage & try one.  (too late in the day, is my excuse !)

Cheers Banjo

[Banjo]

No unfortunately. Definitely not symmetrical !

 

[Thomas Dillon]

1 hour ago, Banjo said:

Have You had this engine running ?  If the block is a 5K, then T.D.C. No 1, will be a bit out, if You line up the crank pulley timing nick, with the timing marks on the camshaft sprocket case.

I can confirm I have had this motor running and it goes like a cut cat. I haven’t had it running since I swapped out the single row chain to the double row. 
 

I think both you guys weighed in on this. I couldn’t get the locator dowel to line up and had to roll the crank back like a tooth to get it all on. 
 

The other finiky thing with this motor is its had the eg. 4k - ***** stamped on the block ground off hahah. 
 

are there any other ways of identifying the block? It goes way harder than any 4K I’ve owned, which makes me think it could be 5k. Although the rumour down the grape vine of previous owners say 4k-u block 5k head. 
 

I think I’ve found a ke70 thermo housing that should have us sorted to shoot water the other way. 
 

Thanks for your input fellas, both of you banjo & altezza always blow me away with your responses. I hope these forums pay you haha!!  
 

I’ve added photos of various angles of the motor for you guys to geek out on if you can figure if it’s 5/4k 

[altezzaclub]

"and it goes like a cut cat."

Toss the downdraft  and get a single 40DCOE Weber on there! If not bike quads!

I don't suppose you measured the bore when you had the head off, or took a picture of the pistons? Dished pistons sound like 5K too, my 4K looked like this-

That was digging the rusted gunk out from around #3 & 4 cylinders, a major reason they overheat and blow gaskets.

I thought that t'stat top would rotate easily. it certainly does in Photoshop!

 

Sounds like a fun build, any idea on the cam that's in it?

 

[Banjo]

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I thought that t'stat top would rotate easily. it certainly does in Photoshop!

The centre line between the two mounting holes, does not pass through the centre of the open area. It will probably bolt down OK, but will leave a slight gap on one or both sides, which will leak or blow, with minimal face to face, one or both sides. I'll try it tomorrow, & see.

Cheers Banjo

[altezzaclub]

You are right! I didn't look at the fine detail, although now I vaguely remember something about it from a  decade or two back.

[Thomas Dillon]

I haven’t had the head off on this motor yet, have be tidying up the body and everything else first as it was in dire need of some tlc. 

Once/if the motor kabooms itself then we’ll give it a good once over. I’ve had a peep down the spark tube on a very peculiar angle and have definitely seen dished pistos. 
 

Even just giving the motor a wee freshen; all gaskets/seals, main seal, twin row, filter, engine mounts, radiator/fan, etc etc I’ve ended up spending a handsome sum ay hahah. It adds up quick. 
 

carbs in good time, we just need to get out there rippin first. 
 

this is the pile of goodies waiting to go back in the car after paint, set a date to have it finished for early September so we’ll see 🤣🤣

had a wee mock up with the new wheels the other day and now I just want it finished