I started today on what, according to the book is an easy job, replacing or rather installing (PO left it out) a new thermostat on my series 1 4.2. I got the nuts off the housing with a bit of work but can’t see how to get the housing off the studs because of the water pump pipe under the housing. What am I missing? Should I be thinking of removing the whole coolant rail or just give up and take off the cylinder head. I’m loath to go that far because the engine runs really well and very smoothly but cool so no heater and I’m sure not optimum ignition since the engine never gets to temperature.
Any advice on how to get this thing off would be appreciated.
You must have an early car with studs instead of bolts. Did you get off all three nuts? there is one hidden deep under the header tank. If so then the only thing holding it on is corrosion/gasket material and that bypass hose that goes to the water pump. Cut it if you can’t get it off. It’s only a $7 or $8 hose - there is no reason to remove the manifold or head (don’t do that just for the thermostat). But you definitely need to have a thermostat in place or you will have problems if you drive the car any distance.
There is a document floating around that gives some ridiculous advice about using a thermostat without a bypass block-off foot. Don’t do it - use the correct thermostat. If you don’t the car will take forever to warm up and then overheat because of the massive Series 1 bypass being open - allowing alot of coolant to bypass the radiator.
Follow rust free Mike’s advice.
You don’t need to take the rail off or the head.
There are 3 bolts holding the bits together; and the hidden one runs the length of the thermostat housing.
I went through this very same thing with my Series II but I snapped the heads off the bolts, and the bolts were also rusted in the housing. It took a lot of penetrating oil, heat, and swearing before it was freed.
For me this kinda turned into where I am at now. the PO didn’t have a thermostat in place so the engine never got warm; which caused excessive skirt and piston wear, now I’ve got a loose bottom end…
Thanks Mike and Mark
Yes my car has studs, not bolts. I can see it would be a whole lot easier with bolts so maybe I will try to get the studs out and use bolts instead. I did get the nuts off the three studs without too much problem so maybe cutting off the hose is the answer though that means that unless I can get the studs off I’ll end up trying to get the housing back onto studs with the replacement bypass hose fouling things.
I’ll get back to it today and report back on what I find and decide.
I replaced mine ('85) recently and snapped off one of the long bolts as it turned out to be completely encrusted with corrosion in the non-threaded part going through the housing. I was happy it was possible to remove the entire manifold. I was able to unscrew the housing from the manifold and tap the bolt out. Darn good thing only one broke, no amount of vice grips or penetrating oil would have gotten that stub out ha!
Yes Martin
I tried using the two nuts method to remove one of the short studs with the thermostat housing still in place but too much corrosion and I thought I’d either strip the threads or shear the stud so I stopped. Maybe once I get the housing off it might be easier. At least I’ll be able to get some penetration oil into there and maybe use a bit of heat as well.
Ian
I can definitely see how it would be a little bit more fiddly to reinstall the tank and bypass hose with studs instead of bolts. But I think it won’t be too terrible if you’re dealing with a fresh, new supple and soft hose.
One thing that’ll make it easier - be sure the hose is right length and not too long. There’s a Series 3 hose made by Gates that I’ve used a few times (on S3’s) that comes too long and makes it hard to install even with bolts if you don’t trim it.
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The book is right, Ian; if you have removed 3 nuts the housing supposedly slides off the studs. The problem with the later cooling set-up is that one long bolt is used - and when corroded; brute force will inevitably break it…
The usual problem is the housing being solidly corroded to the studs, as Mark mention - but hoses must be disconnected from the housing or the pump. Which should not be a problem - or a problem to be solved. Removal of the water rail or head is the last desperate measure when everything else fails…
Thanks all, done and dusted. I cut off the old, stiff bypass pipe and took off the top of the fan shroud plus the breather bits and with not too much brute force I was able to get it off. I was going to try to remove the studs and replace them with bolts but I don’t have a long enough bolt to replace the one long one so I cleaned all the bits and assembled with new gaskets and a new much more flexible pipe and it went together without much drama. I then took it for a spin, 5 miles or so and the temp gauge still never came off cold so there’s maybe something wrong with the sender as well . I have a known good one on another XK engine so I’ll swap them out to see what happens. If not the sender it’s into the wiring we go. How did I ever get time to do this before I was retired?
If you can get the housing off, it will be a whole lot easier. This process for me took about a week to get the housing off. it was a squirt with oil, then wait over night a couple of times. I also took a really big soldering iron, and let sit on the bolts for a while; Then gave the head of the stud / bold a bit of a tap with a hammer.
Eventually it gave up and let go. It was one of those projects that falls under the category of “How hard can it be?” infamous words equating to VERY HARD!
Here’s another trick that I’ve learned and has worked very well. The computer “air” cans used for cleaning keyboards and such. take one of the cans turn it upside down, and squirt the pressurized CO2 liquid onto the bolt / stud. as the liquid flashes off, the CO2 seriously cools the part. I’ve used this to drop in interference fitted bearing when I didn’t have a press, Popped the hub assembly in the oven at 200F degrees then coated the race with CO2 liquid. dropped it right in. once it warmed up to room temp, the race was there in place. Worked like a champ. for every 100F degrees, steel with expand / contract .001
OH, and when it’s cold give it a tap with a hammer to (on the head of the stud then try to loosen it.
The tapping breaks the sticktion between the two parts.
Here’s another one.
Need to expand a part like a wheel bearing on a interference fitted shaft/ thoroughly wrap in several very wet paper towels put in the microwave oven for about a minute or two, you’ll have a part that is damn near 200F degrees. why? well it’s because water boils at 212F degrees. so when the water boils off, it also warms the part. there you have it. 200F part equals an expansion of .002. The part should just drop on.
I just did this on my '87, and had to use a map gas torch to heat up the housing, and long bolt inside of it. Mine was on the verge of snapping off… had it not been for the map gas, it would have.
Not intentionally, when I was a kid working in restaurant I heated up a bowl of soup with the spoon still in the bowl. Bad things happened. Sparks, Smoke, and a spoon melted to the bowl. Not one of my finer moments.
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What you need is an infrared thermometer, Ian. They are cheap and will conveniently give you a precise temp at the sensor - or anywhere else. Very useful…
Unless you know the actual temp the sensor ‘sees’ you are sort of fumbling in the dark. I trust you checked the thermostat before fitting it; ‘new’ does not necessarily mean ‘in working order’ - and only a temp measurement will tell if it is indeed working…
Reconsider replace the long studs with bolts. While they will allow moving the thermostat housing ‘sideways’; the bane of the SIII set-up is the long bolt may snap if corroded. Leaving you with abolt extraction problem - while studs will leave you with only the problem of sliding the housing off…
Not since I was a kid and blew the door off the Microwave in an commercial kitchen. Needless to say that didn’t score me any points with the chef or management. Also the other reason why the 200F degree mark is somewhat important is because once the metal temp gets greater than 200F it can affect the temper which is something I really don’t’ want to do.
Hi Frank
I did indeed test the new thermostat before installation and it worked fine. The engine now “feels” like it’s at the right temperature and the gauge is coming up to just below the normal range where before it hardly got off the backstop. I have an IR thermometer which I haven’t used for ages and of course when I tried it, it won’t work. The battery contacts have broken off, cheap Chinese model, so I;m trying araldite overnight otherwise, as you say they are cheap so a new one is on the cards. What temperature would you expect in say the header tank and the bottom hose and any other temps you think should be taken. The engine is running very smoothly but has too low a tick over, around 200 rpm on the tacho after the AED comes off and at that speed lumpy but it does continue to run. I’ll adjust that up a bit tomorrow.
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For testing of the temp transmitter/gauge combo, only the temp at the temp transmitter base is relevant, Ian. With the engine warmed up it should show stated thermostat opening temp - or thereabouts. If the temp shown is the same as the gauge - the gauge and the temp transmitter are working normally…
Various temp readings can be taken for various purposes - but differences in temps at various places may tell something. The header tank on the engine will likely show the same as at the temp transmitter. The temp at the bottom hose, when compared to the temp at the top hose, basically tells how efficient the radiator works. But those temp differences varies somewhat with factors like air temp and overall coolant temps…
But the infrared is a very worthwhile tool - whenever temperatures have a tale to tell…
Idle should be set as prescribed for the carbs fitted - generally to some 600 - 650 rpms. While the simplest idle adjust is to increase the opening of the throttles with an idle screw - it’s advisable that the full range of carb adjustments is used - including carb synchronization…
That the rpms drops as engine temps increases does indeed mean that the AED is functioning. Which is good - but the AED must be closed before idle is set to spec rpms…
Hi Frank
I got my IR thermostat and checked temperature before and after thermostat and therefor at the temp sensor. Both were at 82 C which is exactly the stated temp for the thermostat to be fully open. Still however the gauge reads below normal. My gauge is not marked in temps but a white low section, dark normal section and red for high. It never gets out of the low white area with an ambient temp in this area today of 12 C. If I short the temp sensor lead to earth the gauge reads full scale so seems that gauge is ok. That only leaves the sensor unless this model car normally reads low. My E type series 2 with the same engine reads in the normal section. I’ll warm up the E Type and measure the resistance of the sensor and do a comparison to try to pin down where the problem, assuming there is one, is located.
Ian
