totally enclosed engine

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This topic contains 19 replies, has 10 voices, and was last updated by  pmossberg 6 years, 5 months ago.

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  • #234813

    greg-press
    Participant

    @greg-press

    I was talking to a car restorer the other day and he said that the engine compartment needs to be kept separate from the rest of the car this would make the car run a lot cooler after looking at pictures of VW beetles the engines are separated. I then looked at td replica’s it appears some are some aren’t. Most dune buggies aren’t. If my LR was factory built they either didn’t seal it off or someone removed the seal. There is no evidence of anything ever being there. Are your engines sealed off from rest of car.
        One other thing not related. My wife and I went to AACA judging school last night and we will be judging our first show this Sunday lucky us we won’t be the head judge there is a lot to it.          

    #257076

    jebarry
    Participant

    @jebarry

    Greg My MG TDr London roadster is the same as yours..

    #257077

    edsnova
    Participant

    @edsnova

    All me tins but there are gaps. I should have more 

    #257078

    phil
    Participant

    @phil

    I separated the cold air side of the engine from the hot side.  I don’t think the temp gauge has ever registered above 210

    #257079

    pmossberg
    Keymaster

    @pmossberg

    Most VW experts will tell you the upper portion of the engine needs to be completely sealed frm the lower (think of it as separating the hot exhaust from the top end).

    Most, make that MOST, TDs have a completely open engine compartment.

    My engine builder told me to not worry about it. As long as the cylinder cooling tin is in place, pushing a car about two-thirds the weight of the original Beetle, he said I’d be fine. The  engine builder runs a VW micro-bus and his engine compartment is not “sealed” either.

    I ran my 1641 for almost three decades with only the cylinder tin.
    And now I’m running the 1776 the same way.
    Neither have had any overheating problems.

    Paul Mossberg
    Former Owner of a 1981 Classic Roadsters Ltd. Duchess (VW)
    2005 Intermeccanica Roadster

    If you own a TDr and are not in the Registry, please go to http://tdreplica.com/forums/topic/mg-td-replica-registry/ and register (you need to copy and paste the link)

    #257080

    mrlmd
    Participant

    @mrlmd

    My car had the tins in place and I made a firewall out of Galvalume material left over from a roofing project, placed forward of the engine a few inches from the fan shroud, screwed into the fiberglass. That effectively separated my engine compartment from the exhaust and heater boxes underneath,  and it dropped my engine temp 10-20 degrees and cured my tendency to overheat. And I live in Florida where 90-95+ degree days are common and have had no problem since I did that.

    #257081

    kentt
    Participant

    @kentt

    mrlmd wrote:
    My car had the tins in place and I made a firewall out of Galvalume material left over from a roofing project, placed forward of the engine a few inches from the fan shroud, screwed into the fiberglass. That effectively separated my engine compartment from the exhaust and heater boxes underneath,  and it dropped my engine temp 10-20 degrees and cured my tendency to overheat. And I live in Florida where 90-95+ degree days are common and have had no problem since I did that.

    Exactly — whether or not you’re having overheating issues without modifying the TDr normal provisions i(which are poor, IMO) s likely dependent on (a) the climate where you live, and (b) where/how the car is being driven.  In cooler climates there may be no problems at all.  In warmer climates, you may be OK as long as you’re just cruising back roads and not getting stuck in traffic.  Or, you may find that its overheating even during highway driving.
    There’s a few issues involved:
    1.  Providing an adequate source of fresh air, if you block off the firewall near the flywheel.  Blocking off that firewall prevents the engine from drawing up hot air off the pavement, or pulling in the hot air that has gone out through the doghouse oil cooler.  But, you must be able to provide an alternate source of fresh air.  Note that on stock VWs that fresh air intake was up as hign as feasible, keeping maximum distance from the hot pavement (which in the Southwest can be 140 degrees or so) and  the cooling air, now hot,  that is being blown out of the engine.
    2.  Preventing either radiant heat from the hot exhaust (which is only inches from the oil pump at the back of the engine) from coming up into the engine compartment, and preventing the cooling fan from sucking outside air up over that hot exhaust and drawing the now hot air into the engine compartment and onto the engine….
    3.  Making sure that the fan-forced air is flowing correctly over the engine, as it was originally designed (and tested) to do.  There’s a lot of potential issues or missing tin that can impact this, such as:
    • The fan shroud itself.  Many aftermarket shrouds do not have the same vanes inside them that split and direct the airflow that the factory shroud does. 
    • Missing  fresh-air hoses or open holes in the shroud where clips that held the spark plug wires originally were, or where mounting screws once were…
    • Factory thermostat, adjusted properly, and the “shutters/vanes” that it controlled in the very bottom of the fan shroud.  These do two things – they warm up the engine to operating temps faster (reducing moisture condensation in the engine oil meanwhile), while also directing the airflow where it is needed…
    • Tins on the jugs/cylinders that direct the cooling air and force it through the fins on the jugs  — all the way around the jug, as much as possible, to avoid “hot spots.”  The stock curved tins from Type III engines work better than the normal Type I tins, as long as you’re not using over-sized pistons/jugs. If you’ve gone over stock size, you’may have to trim those to fit… IMO, this is an excellent upgrade during rebuilds or valve jobs.
    • Finally, a clear exit path to the rear for the now-hot air once it has flowed down past the jugs and push-rod tubes.  The tins below the push-rod tubes are essential, and if you’ve replaced the stock heater boxes with J-tubes, you need something to seal the sides of the area around those tubes to force the air out the rear of the car.  As it leaves from under the car, it serves to help cool the hot exhaust and take that heat out and away from the car also…
    That’s the key points of the VW cooling system, and it all interacts.  For example, I’ve seen that just replacing the old brittle rubber seals around the tin in a stock VW make 15-20 degree differences in operating temps.  All this assumes a properly tuned engine with reasonable compression ratios… too much spark advance makes them run hot, as does too lean a air/fuel mixture.  
    My bottom line is that the factory VW cooling system evolved and was refined over millions and millions of miles of road testing  (the original bug was the most-tested automotive design in history), not counting all the miles driven by all the VWs since.  So don’t arbitrarily change or modify it on a whim.  Stay as close to the stock cooling system as possible… for example, I’ve seen people install an aftermarket oil cooler over the opening for the fan shroud, and actually increase engine temps rather than cool it down more.  
    Here’s some excellent info on VW engine cooling:
    Also realize that when you modify the engine to produce more power, you’re automatically and unavoidably generating more heat, and there’s no escaping that law of physics… so, you need to consider that and try to compensate for it somehow…
    My 2 cents, your mileage may vary… 

    Early FF TDr on 69 VW pan
    Slowly coming back from the ashes...

    #257082

    royal
    Participant

    @royal

    I have all the factory “tin” and have no heating problems.  I do not have a thermostat installed because it was removed by the prior owner.  But there is no seal between the tin and the body and this gap is sizable.  

    That being said, I have thought about excessive heat and I monitor my oil temperature carefully with an oil temp gauge as well as an infrared thermometer.  I live in North Carolina and we do get some sweltering days here.  
    Were I to have overheat problems, I would consider making a seal with an old tire inner tube.  It could be pop riveted or screwed to the existing tin and the fiberglass also to span the gap.  Of course, you would have to be careful and stay away from the exhaust lest you start a nasty fire, but I think it could be done and would be effective.  
    But then, as Kent asks, where would the cool engine air come from?  If your engine cover fits tightly, it might be necessary to find/manufacture some source of make up air.  If you have a rear mounted spare tire, under it might be perfect and would not destroy the looks of the TD.
    Greg, with you living in western NY, I think that you should have no problems unless you do a lot of driving in heavy traffic.  I would almost bet that you are missing some engine tin.  In particular, how about the two pieces of sheet metal that are in the shape of a truncated cone that fit between the cylinders (one on each side)?  Or, when was the last time that you cleaned the engine really good?  I am not talking about the pretty parts of the engine that you see when you open the engine cover.  After I deep cleaned my engine with 3 cans of engine cleaner, my oil temps went down about 15 degrees.  It’s a dirty job, but not hard.  Well worth the effort.  
    #257083

    greg-press
    Participant

    @greg-press

    Royal, When I was growing up we would de-grease engines often. Spray the degreaser on let it set for awhile, hose it off. We would always have the engine running when we hosed it off. The way I would do my LR would be jack it up , put it on stands, remove rear tires, crawl underneath and go to town. Is there anything I should cover and should the car be running.            

    #257084

    kentt
    Participant

    @kentt

    Cover the distributor cap with a plastic bag, so you don’t get water inside the cap….

    Early FF TDr on 69 VW pan
    Slowly coming back from the ashes...

    #257085

    royal
    Participant

    @royal

    I am afraid to squirt water on a running engine, but I guess it is about the same as running through a mud puddle during a rain.  

    I take the distrib cap off and cover the dist with a bag.  Then take the air cleaner off and cover the mouth of the carb with duct tape.  I also run a band of duct tape around the generator cooling slots.   Then have at it.  I use 3 or 4 cans and get in there with a brush also.  A power washer works pretty good also.  As usual, the hardest parts to get at are the most important:  the cooling gills around the jugs and the push rod tubes.   The dirtier you get the cleaner your engine will get and the happier both of you will be.  When I overhauled mine, I was surprised at the amount of dirt that had cemented itself to the blades of the squirrel cage fan.  Probably almost impossible to get off without removing the fan shroud.   No matter what every little bit helps.  Good luck.  Don’t forget to plug up all the holes in your shroud afterwards and put good air sealing caps on your spark plugs.  

    Are you sure that you have all your engine tins?
    #257086

    greg-press
    Participant

    @greg-press

    I think the only tin I am missing is the bottom tin. I did buy a heat shield for the exhaust. I don’t know what tin fits or where to buy it.

    #257087

    prisoner6
    Participant

    @prisoner6

    I just picked up a louvered firewall. I am doing a body off reassembly and have not yet installed the rebuilt engine. The trans-axle, driveshafts and wheels are installed. Does the louvered firewall go behind the dome of the transaxle or over it? The Big Question: Should I be using the lovered firewall? Sure looks good.

    #257088

    royal
    Participant

    @royal

    A “louvered firewall”?   Is this is a perfect example of an oxymoron or what?  

    My 2 cents is: find some other use for it.  If for no reason other than it would significantly increase engine noise in the cabin.   
    #257089

    royal
    Participant

    @royal

    Greg, this video shows the tins and how to install.  

    #257090

    kentt
    Participant

    @kentt

    IMO, probably the best compromise sealing we can do on these TDrs is to try to seal the rear of the engine at the crankshaft pulley to block the exhaust heat from entering the engine compartment, and to seal the sides over the valve covers.  Then, leave the firewall open for the cooling air intake. If you block off the firewall area, then I’d suggest vents/louvers in the sides of the engine lid — what would’ve been the sides of the MG’s fuel tank.  

    Note that the original VW seals were two layers of rubber. One flap went under the tin, while the other laid on top of the tin.  Something similar would be fairly easy to fabricate…

    Early FF TDr on 69 VW pan
    Slowly coming back from the ashes...

    #257091

    mrlmd
    Participant

    @mrlmd

    I used metal tape to seal off the opening between the tins and fiberglass floor of the engine compartment. And there are matching holes in the rear deck lid (fake gas tank) that match those on the spare mounted to it, to provide the fresh air intake. That’s why I don’t recommend a spare tire cover (for appearance sake) as you are blocking off the fresh air intake if you put that on.

    And I totally agree with everything Kent said.
    mrlmd2013-07-27 11:11:52

    #257092

    newkitman
    Participant

    @newkitman

    Just thinking out loud here. What about the rear seal around the engine compartment of a beetle? Possibly fitted and riveted to the fiberglass?

    Allen Caron
    VW based 53MGTD - "MoneyPenny"
    "If one thing matters, everything matters" - from the book The Shack

    #257093

    kentt
    Participant

    @kentt

    Allen, that’s what I’d try first, I think…

    Early FF TDr on 69 VW pan
    Slowly coming back from the ashes...

    #257094

    pmossberg
    Keymaster

    @pmossberg

    Some of the Speedster guys say the rubber gasket from a VW microbus works better than the Beetle’s.

    Paul Mossberg
    Former Owner of a 1981 Classic Roadsters Ltd. Duchess (VW)
    2005 Intermeccanica Roadster

    If you own a TDr and are not in the Registry, please go to http://tdreplica.com/forums/topic/mg-td-replica-registry/ and register (you need to copy and paste the link)

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