16 replies to this topic

[jabos7]

I'm seeking your thoughts on my 998 in my '73 Mk3-all stock.  Freshly rebuilt with only timing and carb adjustment runs, plus one trip around my block.  My first sign of trouble was seeing some oil around the block ID.plate, then when I pulled my radiator cap it popped off in my hands from the internal pressure cold, 2 days later!---I'm using a waterless coolant that should not create any pressure at all.  So far there is no signs of oil in that expensive coolant, or coolant in the oil.  Today's running revealed oil/bubbles seeping out between the head/block over the cylinder 2,3 area.  -I'm gutted.

 

I had a machine shop do my exhaust valve seats for unleaded, and they supposedly milled the head (flat).

I used a M.Spares AJM1250 head gasket set for the build, and when I mounted the gasket I sprayed it with some Permatex copper seal spray -meant to fill imperfections and seal better, etc.  And yet disaster.

 

Unless the head has an un-noticed crack or warp, could the copper spray be a possible suspect?  Maybe creating a high spot somewhere--I just can't imagine it.  Heater line blankout plate on the head creating coolant flow pressure? doubtful.

I went with flattop pistons to bump up the compression a bit -should I have used a competition strength head gasket? 

Any and all thoughts are appreciated.

 

Jeff-- Maryland/USA

 

[jabos7]

subsequent compression test on my still warm engine gave me:

 

1 --160psi

2--150

3--155

4--155

 

Maybe a hint there where the bubbles/oil were showing up, but overall I should have been pleased with my build result.

 

I even re-torqued my head bolts, and went to 52 ft.lbs instead of book 50---but no change.

 

This might make me walk away from the whole thing for a few months unless I can come up with a worthwhile checklist of

ideas before I yank that head and head to a shop.   --All suggestions welcome!!!  -J

[nicklouse]

waterless coolant! why? it is *******. it has a worse heat transfer ability than a good 50/50 mix which in its self is worse than pure water.

 

over torqueing is never a good idea as you dont make things better you just make things worse. and 50 is only for the latest studs.

 

pull it and see what is going on.

 

never used that gasket or that spray so cant comment.

[Spider]

I think you maybe over-thinking what you've seen. I really don't think there is an issue.

 

Drain your coolant and fill it with Water. This is to get the gasket to seal. Leave the water in for at least a few heat cycles, then drain.

 

I would strongly advocate again most (all) waterless coolants as well. The only ones I've seen are in fact 100% Glycol and for heat Transfer, it's not very good at all. Everyone I know of who has tried in any engine that was not made specifically for it has found they either run hotter or overheat much easier than with coolant / water mix. I get your intentions by using it, but, in an A Series Engine, it's no good.

 

Where you were seeing Oil from the Gasket, there is no Oil near there. There's a Oil Pressure Feed at the back of the head (near the By-pass hose in fact) and non-pressure Oil Return at the back side of the head. I'd say, what you saw was some residual Oil from one of the stud holes.

 

Unless you'd like to take the head off & basically re-do all you've done here, leave the nuts torqued where they are, you'll likely be OK with that. I would however recommend a re-torque to the same as what you've done now after a few heat cycles.

[unburntfuelinthemorning]

I had some weird radiator pressure issues when I first got my Mini which resolved when I changed the thermostat.  The one that was in there didn't have the one way toggle valve thing in the rim or a hole where it is supposed to be so the coolant was doing odd things when the engine cooled.

[Rorf]

Stick to the basics, no fancy coolants and copper gasket sprays - just use a good quality Payn head gasket.

[unburntfuelinthemorning]

Minispares say the Payen gasket for small bores is obsolete but sell there own version instead now.

[jabos7]

Thanks to all for the comments - especially Moke, -great to hear from you!

 

My relatively consistent compression test does give me pause, not showing any significant drops.  I've thought about doing it again and letting

the tester tool stay engaged a little longer, maybe 15-20 seconds, and watch for a drop off on each cylinder.

 

The oily bubbles pushing out from the head gasket (very small but weird) still concern me.  And I'm willing to give up the Evans coolant, but

I'm worried that water or a 50/50 will build even more pressure after heating and blow a hose off.  My cap comes off in a very pronounced poof/pop.

It's almost as if the action of the spring seal in the cap is too strong.  But this coolant should not make hardly any pressure, and should allow

you to remove the cap at full operating temp without fear of boilover.

 

The idea of the thermostat hole is intriguing, and might explain why no oil has shown up in the coolant from the head gasket unless

the amount is still too small to detect.  I'll look up my receipts to check the part number against the supplier to see how mine was made.

 

I reeeaaally don't want to pull that head unless absolutely necessary, but my clues so far have me stumped.

[cal844]

I'd be changing the thermostat so you know it works then also change the coolant to normal antifreeze and water.

I think the radiator cap is actually ok as its holding pressure.

Post edited

Edited by cal844, 12 November 2019 - 12:13 PM.

[Spider]

Cheers jabos.

 

Any coolant, even the waterless ones will build up a pressure in the cooling system, so what you've found there don't poke me in the eye.

 

If it were me, I'd drain the coolant, fill with water, do a few heat cycles, drain and fill with coolant. Let it sit over night, re-torque the head (to the 52 ft/ lb you've already used), set the tappets and then see how you go.

[jabos7]

So let it be written, so let it be done.  --I'll yank that coolant out asap, and run a couple water fillings through and see what happens.  Before

I yank the head (if things stay sour) I'll check that thermostat for the relief hole as well.

 

I'm more than willing to try anything to prevent doing another head gasket on a fresh rebuild.  Have patience and I promise to follow-up, but we

just had a front come through and our lows will be in the 20s tonight, so I'll give it a day or so to moderate so that she doesn't sit in an

unheated garage with straight water in the block.  Fingers crossed, and toes, and...........

[jabos7]

Well, as suggested -and wisely so- I drained the waterless coolant out, ran straight water for 2 heat cycles and then put my 50/50 antifreeze

mixture in.  I don't get it - but success so far.  I let it run and rev for 15 min, no oil seepage bubbles at the head/block seam.  Then I let it completely

cool, to duplicate the original scenario, before pulling the radiator cap off --no "pop" pressure!   Amazing.

 

Further research, especially at a competitor website for norosion.com, gave me some hints.  My waterless is thicker than 50/50 and therefore

is harder to move through the system.  This puts stress on the waterpump and backs things up trying to get through the radiator fins.

 

Also, and probably more significant, this product easily runs 80-100+ degrees hotter in the head.  --That scared me even more, thinking I

had already warped that thin little iron head.  But the 50/50 seems to have made the 998 happy again.

 

Lesson learned.  I've still got to get a few more heat cycles before I'm comfortable, but at least I have some hope that I may not be taking

everything apart.

 

Thanks again to all!  -J

Edited by jabos7, 16 November 2019 - 02:47 PM.

[panky]

Was it this article? Never intended to use Evans but this put me off completely

 

http://www.norosion.com/evanstest.htm

[johnR]

Re the oil you were seeing, could it have come down from the rocker cover gasket and run around the head/block join?

[Spider]

Nice work and thanks for the feedback.

 

If it's a Glycol based coolant you are using, then even a 50 / 50 Coolant Mix is getting 'heavy handed' unless your in a very cold climate now or running an Aluminum Radiator?

 

Glycol is a poor heat transmitter, it's slow to absorb heat and slow to release it. For most applications and climates, a 30 / 70 mix is usually all you'll need.

 

I do run Copper Radiators and would run an approx 25 / 75 - 30 / 70 mix all year round, but our winters aren't that cold either.