Sandy Gibson Posted May 31, 2022 Report Share Posted May 31, 2022 Just fired up my mk3 engine after rebore. All went well, good compression, water circulating but when I checked the oil it’s very milky. Also bubbling through the rad with the cap off. Thinking of taking the head off, getting it skimmed and trying again with a new gasket. Does anyone think this should be the way ahead? Alternative is to pull the engine and I haven’t really got the time (or the enthusiasm at the moment!!) to do that. Any advice would be much appreciated. Thanks Link to comment Share on other sites More sharing options...
NonMember Posted May 31, 2022 Report Share Posted May 31, 2022 If it wasn't suffering these symptoms before the rebore then it shouldn't need a head skim now. However, it does sound like your head gasket isn't sealing properly. What make did you use? Are you sure it was the right one? (Fitting the late gasket on an early engine will give the symptoms you have, plus some leaks.) Link to comment Share on other sites More sharing options...
Sandy Gibson Posted May 31, 2022 Author Report Share Posted May 31, 2022 Used a Payen gasket without any dressing. I bought the engine for repair. It had broken piston rings caused by a lip on the top of cylinder bores but no head problems as far as I know. Block has been rebored to +040 Other than a good de carbon and polish the ports, didn’t touch the head Link to comment Share on other sites More sharing options...
NonMember Posted May 31, 2022 Report Share Posted May 31, 2022 49 minutes ago, Sandy Gibson said: Used a Payen gasket without any dressing. Which type? My thinking is that a warped head would cause you to lose compression, which would make it not run. Ditto for any debris or failure to fully clean the old gasket off. Corrosion on the block face would have been spotted by the machine shop, and I'd kind of hope that such damage on either face would have come to your attention while assembling it. So that leaves the most likely explanation being that you've been sold a late Mk4 gasket for a Mk3 engine. You can tell them apart because the late one has an extra tab the sticks out the back of the engine. (It also has raised fire rings to fit the block recesses, but you can only see them with the head off) Link to comment Share on other sites More sharing options...
Wagger Posted May 31, 2022 Report Share Posted May 31, 2022 If the engine showed no signs of water in oil when you stripped it, the head should not need skimming. Make sure that you are using the correct gasket and torque the head down carefully using the rebuild bolt tightening sequence. I had a problem with a 1500 FWD engine because I failed to observe this. Also, when the head is off, check that no waterways are leaking into oilways if you can. Skimming the head would require removing all of the valve gear. Link to comment Share on other sites More sharing options...
Nick Jones Posted May 31, 2022 Report Share Posted May 31, 2022 A Mk 3 Spit engine should be a flat top block without recesses around the bores. It is possible to fit the gasket for the recessed block engines by mistake, identifiable by the tag stick out at the back. Because the fire-rings around the bores are thicker this usually gives good compression but oil and water leaks internally (and sometimes externally) that could lead to milky oil, but not usually bubbles in the header tank Nick Link to comment Share on other sites More sharing options...
Sandy Gibson Posted May 31, 2022 Author Report Share Posted May 31, 2022 It’s definitely a Mk3 engine and I can’t see any tags at the rear of the head. Attached a couple of pics of block and head prior to assembly. If the gasket has failed should it be obvious when the head is off? Link to comment Share on other sites More sharing options...
Nick Jones Posted May 31, 2022 Report Share Posted May 31, 2022 That all looks good to me. Gasket fail point might not be especially obvious given the short running time Another way of water getting into the oil is that the studs that hold the rocker cover on sometimes go right through to the water jacket and may need a bit of sealant on the threads. A couple of the studs that hold the timing chain cover in place also go through to the water jacket (the top two or three on the manifold side) though it’s rare to get an internal leak without an external one too. Neither of these would explain the bubbling in the header tank. Do you actually get an exhaust smell from there? Are you actually loosing water or not enough run time to tell? Did you re-use the original mk3 head studs? If not you need to make certain the nuts aren’t running out of thread before the head is fully clamped. Also it’s essential to use top quality nuts with hardened washers under them. Or better still, the flanged nuts available from Mini Spares which are a more reliable option in my experience. Nick Link to comment Share on other sites More sharing options...
Sandy Gibson Posted May 31, 2022 Author Report Share Posted May 31, 2022 Thanks for that Nick I sealed the timing chain studs and also a water pump one which went straight through but I didn’t know that the rocker cover studs could go through. I had the engine running with the cover off but didn’t see any water coming up. The bubbling in the header tank was more of a foam on the surface followed by some large bubbles. Might be air trapped in the system being released. I’ll run it a bit longer tomorrow and see what happens. Used mini spares flanged nuts on original studs but don’t think thread length was an issue. Sandy Link to comment Share on other sites More sharing options...
Nick Jones Posted May 31, 2022 Report Share Posted May 31, 2022 2 hours ago, Sandy Gibson said: I had the engine running with the cover off but didn’t see any water coming up. They don't all go through - it depends on the casting. If it was doing it I think you would have seen it running with the cover off. Worth running some more - it can take a while to get the last of the air out. If there are enough combustion gases escaping into the coolant to blow lots of visible bubbles you can usually smell it as exhaust. Could the milkiness of the oil be lots of fine air bubbles rather than water mixing? Link to comment Share on other sites More sharing options...
Sandy Gibson Posted May 31, 2022 Author Report Share Posted May 31, 2022 I’ll run it again tomorrow and see what develops. Good thought that the colour of the oil could be fine bubbles but it looks like emulsified oil to me! Sandy Link to comment Share on other sites More sharing options...
DanMi Posted June 1, 2022 Report Share Posted June 1, 2022 bubbles in the water could be caused by a coolant hose not fully tightened and sucking in air. I had this when I rebuilt my mk2 engine and had a few panicked moments, wouldn't explain the oil though Link to comment Share on other sites More sharing options...
dougbgt6 Posted June 1, 2022 Report Share Posted June 1, 2022 13 hours ago, Sandy Gibson said: It’s definitely a Mk3 engine and I can’t see any tags at the rear of the head Sandy, Just to be very clear the tab is on the gasket, (this may not be a Triumph gasket! But recessed head gaskets are identified by the sticky out bit at the back) If your gasket's got a tab it's the wrong one! Doug Link to comment Share on other sites More sharing options...
Sandy Gibson Posted June 1, 2022 Author Report Share Posted June 1, 2022 Thanks Doug but definitely no tag on the gasket! Wondering if anyone can suggest any more tests I could run while the engine is still running and before the head comes off? Sandy Link to comment Share on other sites More sharing options...
Clive Posted June 1, 2022 Report Share Posted June 1, 2022 Can you post a pic of the oil? When I have "played" with engines, and managed to get water into the oil, it does indeed emulsify, but once run up to temperature for a while, it clears as the water boils off. Persistent bubbles in the rad not great, but worth checking hoses as per Dans experience. But sound unusual if water getting into oil, and air into water, Usually one or the other. Link to comment Share on other sites More sharing options...
Sandy Gibson Posted June 1, 2022 Author Report Share Posted June 1, 2022 Thanks Clive. Bottom of the dipstick shows the problem! Link to comment Share on other sites More sharing options...
Pete Lewis Posted June 1, 2022 Report Share Posted June 1, 2022 as this was the problem before the head came off and its back again there is some careful work needed to find how this is happening but did you flush clean the sump after the initial failure as any moisture in the sump will soon emulsify the new oil daft question ....you did change the oil ??? Pete Link to comment Share on other sites More sharing options...
Sandy Gibson Posted June 1, 2022 Author Report Share Posted June 1, 2022 Thanks Pete Engine has been rebuilt after re-bore. After start up, ran for about a mile to warm up then ten minutes or so fiddling with timing. After that I checked the oil to find the horror! Have not yet taken the head off although that clearly needs to happen. The engine still runs and I am just wondering if there could be any useful checks I could carry out at this stage before the head comes off. One of my many concerns at this stage is that I take the head off and there is still no clue as to what went wrong! I bought the engine as a spare to rebuild. Only known previous issue was broken piston rings ( hence rebore). When I originally stripped it prior to the rebore, I did have a good look at the old oil and it seemed OK so I’m guessing it had no head/gasket problems. Thanks for your help Sandy Link to comment Share on other sites More sharing options...
johny Posted June 1, 2022 Report Share Posted June 1, 2022 I take it youve done another compression test since the problem arose? You could also do a pressure holding test on the coolant system although of course theres many places that can leak.... Link to comment Share on other sites More sharing options...
Pete Lewis Posted June 1, 2022 Report Share Posted June 1, 2022 all a bit unfortunate but dont discount the silly things like what oil was used , could it have had water in it was the sump cleaned out after the last refill and mayo episode check the coolant level is it dropping or not photo of the head gasket but youhave not run long eneough wiith either to give any good clues just think out the box before you jump to "its the head gasket " whats wrong here may not be that simple Pete Link to comment Share on other sites More sharing options...
trigolf Posted June 1, 2022 Report Share Posted June 1, 2022 One of the staff on Practical Classics had a problem with his TR6, despite being rebuilt very carefully by a reputable engine builder. The symptoms were the same - mayo etc. He even swapped the head and rebuilt again. Same problem occurred. In desperation, they stripped the engine, sump off and finally spotted a tiny hairline crack in the block water jacket. Link to comment Share on other sites More sharing options...
Sandy Gibson Posted June 1, 2022 Author Report Share Posted June 1, 2022 I’m reluctantly coming round to the idea that it’s more than a gasket problem. I took a long time with this rebuild and I was pretty meticulous about getting everything right. Does anyone have an idea of how much water it would take to emulsify a sump full of new oil? The engine only ran for about 10 minutes from start up and I am guessing that even with a blown gasket, not a lot of water would escape. During that 10 minutes I did top up the header a couple of times but assumed it was because of air locks escaping from the system . Link to comment Share on other sites More sharing options...
RogerH Posted June 1, 2022 Report Share Posted June 1, 2022 Hi Sandy, this may be a silly idea but here goes- Remove the sump. Assemble the top of the engine Pressurise the cooling system and look for water leaks underneath. Roger Link to comment Share on other sites More sharing options...
NonMember Posted June 1, 2022 Report Share Posted June 1, 2022 1 hour ago, Sandy Gibson said: Does anyone have an idea of how much water it would take to emulsify a sump full of new oil? Not very much. The emulsion can be very misleading, to the extent that you can get nasty mayo from condensation alone. Link to comment Share on other sites More sharing options...
Sandy Gibson Posted June 1, 2022 Author Report Share Posted June 1, 2022 Thanks guys. All suggestions welcome! I had assumed that a significant (whatever that is!) amount of water would be needed but if not, then I’m leaning back towards the gasket failing or more likely my stupidity somewhere! Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now