Welcome to our resource for MG Car Information.
MG Midget and Sprite Technical - Engine not starting after head gasket change
Posting in the correct forum this time. I have got to the bottom of the starting issue I had after changing my head gasket (and posting a request for help in the general forum!).
I had narrowed the issue down to fuel delivery. Looking at the carb did not highlight any issues, it all looked fine. So I thought I would give the manifold manufacturer (Maniflow) a call to see if their new manifold was so radically different to a normal LCB that I needed to retune the engine. The very helpful man (helpful because I didn't buy the manifold directly from them but through Kim at Magic midget who were cheaper), suggested an air leak. Investigating, I realised I had not fully tightened the inlet manifold. When tight, it was better but not perfect. finally I realised that the exhaust wrap was preventing the inlet manifold from seating against the manifold gasket properly. I have removed the exhaust wrap from the first bit of the centre pipe and it runs fine now.
And sounds great...
Can't wait to get the seats and roll cage in and get her out on the road again.
|Glad you got it sorted Dave, just in time for the better weather to come - some time soon!|
Satisfying isn't it?
|Well thats not a good thing|
Btw... congratz on gettimg her started and running agian
BUTT BUTT BUTT... Your going to have some bigger issues in the near future
EXHAUSTE WRAP .... thats a No No. To issues with exhaust wrap
1. It localizes ALOT of heat next to the head Where the exhaust header meets the head and and that can cause all kinda of issues from cracked heads to fuel vaperization on the back side of the carbs thats not shilded
2. Condensation... this is the big one because there is a heat transfer esp in spring and winter you end up with condenstation and it builds up fast and heat wrap wont allow thst mosture to wick off so all that mositure settles in and around the exhaust manifold causeing a very technical term we refer to as...
You can identify this as a brownish red substance that eatting the jesus out of your exhaust manifold...haha
Anyway... save yourself alot of cash and get that wrapping off of there esp before spring flowers start to bloom
That said... if it were me because im considering using heat wrap... only apply it for the heat of summer july and augest and get it back off... my thinking its super hot outside so the exhaust system will cool down much slower and reduce the amount of any heatt transfer into moisture and with the exhaust being super hot in the bad breathing engine bat this will help to cool temp
My thinking is to apply some copper loops of wire on the exhaust manifod pipees next to the head like a heat sink then start the wrap several inches away from the head inorder to minimise local heat buold up next to the head
But that not set into stone yet and the last 3 years ws have had somewhat mild summers compared to the norm ... so not an issue as of yet
Anyway give it some thought
|Prop and the|
|Hi I bought a new LCB from Maniflow and they did not recommend wrapping it for the reasons outlined by prop. Principally the problem with localised heat around the head.|
They recommended coating it to reduce heat. I went for Zircotec not cheap but very durable and promises of up to 30% underbonnet heat reduction.
The other alternaltive was to leave it in the bare metal.
Maniflow talked me out of Zircotec as it was expensive. How much was it?
|Just out of interest, my LCB was also wrapped, but I removed it on the basis of thinking that the main object of an exhaust is to remove the exhaust gases as quickly as possible from the engine. Keeping heat in at the exhaust manifold by wrapping may tend to result in an higher temperature and thus pressure of the exhaust gases than would be if it were unwrapped. This in turn may resulting in increased backpressure and thus less freeflow - both of which are undesirable.|
I agree with the unwanted heat at the head, but it is also the repeated cycling/thermal stress undergone by a wrapped exhaust at elevated temperatures - as the radiant heat path to atmosphere is blocked - that can also cause cracking, especially at any welds.
It ended up at just shy of £220 incl VAT! which was roughly the cost of the manifold.(LMO31 stage 2) I went for the basic option which meant it was black.
Cam Coat were also recommended by Maniflow.
|The coating may well reduce underbonnet heat but it may still present issues with heat retained in the head, thermal stress and thermal efficiency of combustion. |
Is underbonnet heat so much of an issue that it is worth taking the risk of increasing the occurrence of all these undesirable elements? If so, personally I would check out whether the engine is intrinsically running too hot - due to poor cooling, tight valve clearances, timing etc etc rather than insulate the LCB.
|Mark do you have any technical references that allude to the 3 problems you mentioned?|
I ask as ceramic coatings are widely used in all levels of motorsport and I would not expect that if those problems were prevalent.
The heat is in the exhaust gas which transfers to the exhaust manifold as it passes through it. With a thermal coating the heat is still in the exhaust gas but the thermal coating reduces/significantly reduces the heat transfer to the manifold and likewise the head which is bolted to the manifold which isn't as head - the head should run cooler/put less head into the cooling system.
I don't have any technical references as my comments are an opinion for which you are free to disagree with. However, to expand - any form of insulation (ceramic coatings included) may lead to increase in head temperatures and thus lead to all the problems mentioned in previous posts. Retention of heat in the exhaust manifold due to an insulation coating may also incur undesirable thermal stresses at elevated temperatures - especially weld cracking. In addition, transfer of further quantities of this head heat into the inlet manifold leads to a less dense mix resulting in decreased efficiency. These issues would not be as bad as if wrapping, but IMHO, there is a risk nevertheless.
As regards ceramic application in motorsport, I would suggest that they may be more prepared to take the risk of these undesirable elements due to the higher risk of increased exhaust temperatures damaging things in their more complex arrangements.
As for the link - I never place too much faith in manufacturers singing their own praises.
|Mark I think you misunderstand what the ceramic coating does, and how it works. |
'Retention of heat in the exhaust manifold due to an insulation coating' is wrong. The exhaust manifold doesn't retain heat, it doesn't get as hot, period. The heat stays in the exhaust gas and goes down the pipe.
I don't buy that. You are still retaining heat in the exhaust gases which in themselves act as a medium by which heat is retained in the head/ports. Allowing free and easy heat transfer across the manifold to the atmosphere - like a domestic radiator - will allow this heat to dissipate more easily. In other words, keep the LCB bare.
|I understood that the best option was to coat the inside with the ceramic coating as well as the outside.|
Camcoat as Bob noted list the internal coating systems.
|Richard...you beat me to it|
Yes you HAVE to coat the inside of the exhauste manifold with ceramic as that will reflect rhe heat back into the pipe
If you coat the outside then the heat will soak into the metal of the header and will leach out and thur metal and act as a radiator and keep disapating heat into thw engine bay
Doing the out and inside is ideal...but doing rhe inside is a must if your doing ceramic
|Prop and the|
|Ceramic coatings are really only relevant if you are after out and out performance for some sort of competition, or maybe are "sensitive" to style just for the sake of it. For road use, even with increased power output, I really don't see the point of going to the expense of ceramic coating header pipes.|
|I am certainly not technically qualified to understand the ins and outs of heat transfer. I just know the under bonnet heat is higher than it used to be. I have had the same engine in there for 20 odd years and it runs well (well it did until the break in when they nicked the electrics amongst other things). I have noticed the temperature creeping up over the years and it was suggested that modern fuel runs hotter than in times past mainly due to an increase in ethanol. I wanted to address this if possible as I use the Frog for touring abroad more now often in warmer climes.|
The old manifold was an original Leyland ST part which I had hot aluminium sprayed mainly to preserve it. It gave up the ghost at the end of last season as the welds had cracked and the pipe had distorted. The very helpful chap at Maniflow (who told me they made the original ST manifolds) suggested that a ceramic coating inside and out would reduce heat and also preserve the manifold and protect it from the elements. As I mentioned he suggested two companies who provide the treatment. I don't believe he was touting for business on their behalf but was being quite honest about their services. He was clear that wrapping was not good. I hope to have the Frog operational by April with the new manifold so will know how the cookie crumbles.
most of us are running on more ethanol than years ago but are not seeing it get too hot under the bonnet.
I'd be looking at the engine cooling first, water and oil sides, then there's the timing and running of the engine, exhaust partial blockage, brakes binding, etc..
I'm with Guy, for a road car even with more power than standard I think there'd be any real gains for cost - perhaps we're wrong about that, anyone got any data for standard or mild states of tune?
The engine is modified, but it always has been and all the usual things like cooling (new rad) timing( rebult dizzy) mixture (set up on roliing road)Brakes (all new original parts) are is good order. It has a oil cooler. My observation of increased heat is purely based on the change I have noticed over the 40 years of ownership. I claim no expertise at all. It just seemed an approach that would preserve the new manifold and preserve it a bit longer.....
If your intent was to reduce underbonnet heat and preserve the manifold for longer then a ceramic coating may well achieve that.
However, I think you need to identify the root cause of your gradual overheating and solve it, as you haven't really cured this issue by applying the ceramic coating, merely placed an expensive sticking plaster over it.
I may be over-cautious, and the risk may be minimal, but I would worry a little that a combination of allowing the problem to continue and applying the ceramic coating could lead to continually increasing the head temperature to unfavourable levels and risk damage to the head/ports/valve seats as well as increasing heat transfer to the inlet manifold via the head - to the detriment of efficiency.
interesting, as you know I'm no expert on anything but I agree that you probably shouldn't need to coat the manifold so may have an underlying problem that needs finding.
Obviously 40 years of ownership gives you lots of knowledge and experience of your car so I'm not trying to tell grandma how to suck eggs just thoughts.
I hope you don't mind me asking the following - what are your observations of increased heat, physical feel of heat, the temp gauge, etc., and what makes you think this is excessive heat?
You've got a new rad, did you thoroughly clean out the rest of the heating/cooling system including the engine block drain hole and matrix (you probably seen I have a simple thorough coolant cleaning system).
I'm just wondering about a localized overheating for some reason as an oil cooler might often over-cool in some parts.
What have you added or taken away or changed since you first noticed the increase in heat that made you concerned, how long ago was this?
I'm not saying necessarily in your case but even things like moving the number plate or horns or adding lights can make a difference.
I know it's an extreme example but my mate told me about someone we know who had his Cobra replica for a number of years and when it was on run in France just after it'd been rebuilt from his son crashing the car and he was getting very concerned because it was getting much hotter than it used to and he kept stopping to check things slowing the progress of the other cars with him. Finally my mate got fed up at a stop and removed the rally plate from the front and the car and it's owner cooled down. I know myself it's often easier to spot what's up on someone else's car than your own.car
|For me... i had mine coated on the outside before i learned it really needa to be on the inside to control high heat temp|
For me...its not a mexhanical issue its an enviormental issue that raises the under bonnet tempitures ... the after market manifold is the source of most of the heat in my engine bay and for 2 weeks to 6 weeks in july and augest the temps under the bonnet just sore to dissing hieths and make driving the amerian left handed midget unbearable because of the alinmant of the exhaust pipe not to mention heat related issues like vaperisation and electrical ignition problems
Which is reall a air flow design issue more rhen anything... air gets it but cant get out and so it just heats up
But controling the maniflod heat you can control the bay heat during that worst part of summer when the temp never drops below 90* F.
Luckly the last 3 years our summer has been mild and the midget a joy to drive
This year i fear the worst..mid feb and its 79* currenty a new record high by 8* today... may have to turn on the AC if it keeps climbing today
|Prop and the|
|<<<This year i fear the worst..mid feb and its 79* currenty a new record high by 8* today... may have to turn on the AC if it keeps climbing today>>>|
Looks like this could be corrected for you in the next couple of days Prop!
It is missouri the show me state which should be changed to ... if youbdont like the weather, wait 5 minutes ...haba
Im sure we ciuld have 3 feet of blizzard snow weather in march its not outside the coloring book lines..ive seen that happen from time to time
|Prop and the|
|Prop, I had just watched an international weather forecast which seemed to say there was a lot of snow headed your way in the next day or two. Stock up, keep warm and safe!|
|I noticed thst storm also...it looks like it will all go north by several hundred miles...the big fear hear will be tornadeos and lots of wind|
Im glad i dont live in iowa.
|Prop and the|
|I think prop has summarised my thoughts that its environmental but possibly also fuel composition changes. I don't think its anything to do with the engine or car generally as nothing has changed. When I fitted the new rad, I replaced all the hoses with NOS items (not that nasty new rubber!) and carefully flushed the block made sure it was all running clear. I have always renewed the antifreeze every two years so there was little corrosion anyway.(Like Nigel I am a believer in the good book!) The water pump was only a couple of years old and was a high capacity one with a cast impeller.|
Its not a sudden increase in heat but a gradual change. for example 20 years ago it would quite happily idle in traffic (there is a lot in London!) but over the years I have noticed for the same idle period the temp gauge gradually creeping up beyond the figures I had seen in the past. Under bonnet temperatures also seem higher to me.
The need to renew the manifold presented an opportunity to arrest the change as I perceived it. The suggestion that the ceramic coating would help seemed to me anyway worth exploring.
|The suggestion that the ceramic coating would help seemed to me anyway worth exploring|
Yepp....but remember it needs to be on the inside to be most effective...to reflect the heat back into the header pipe...next to the heat its self
Think of the space shuttle it was covered in ceramic tiles ...NEXT TO THE HEAT...Had the tjles been on the inside the heat wojld have burnt the shio but kept the fly boys safe from burning so they could die hitting the ground with out a shuttle
So the ceramic has to face the heat to reflect it NOT TO cantain it
|Prop and the|
I have ensured the internals have been coated as per the company's recommendations
|Fair enough Bob. Bear in mind USA petrol can have a lot more than the up to 5% of ours.|
Perhaps with yours, gauge aging, wear/tear or adjustment of components.
It's only very recently that I've found a really sweet spot on mine idling even after buying brand new SU carbs some years back. Previously I kept the tickover a bit fast as I didn't like the feel of the tickover lower, I don't know why it's suddenly dropped into grove but no doubt it'll be wrong for summer - the beauty of carbs and an old design of cooling system, over cooled when moving, under cooled when stationary.
|You may be right Nigel|
following the theft of all the instruments I have had to buy a replacement reconditioned temp/oil pressure gauge, It may read differently. The one stolen was the original gauge made in 1960!
This thread was discussed between 20/02/2017 and 23/02/2017
This thread is from the archive. The Live MG Midget and Sprite Technical BBS is active now.