andyborris
Posted a lot
Freedom is just another word for nothing left to lose.
Posts: 2,220
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Nov 30, 2023 18:18:57 GMT
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I'm still curious about the water pump, take the top hose off the rad and start the engine, is the water being pumped out of the hose? I have a cunning plan.... Will try this, also doing the same with the manifold to heater hose. Heater hose when cold, (it's also the pump bypass), then when warmed and thermostat open (hopefully) the top hose. Then wiring a override switch for the fans, which aren't switching on. Then try it with rad shroud and fans removed, to see if the (possibly) reduced airflow through the rad is the cause. Although I think at even 30 mph the airflow through the rad and shroud should overcome the restriction of the shroud and fans. If I have a spare thermostat gasket, I'll try it without the thermostat too. Maybe after I test top hose flow? |
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andyborris
Posted a lot
Freedom is just another word for nothing left to lose.
Posts: 2,220
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Nov 30, 2023 18:19:59 GMT
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I'm still curious about the water pump, take the top hose off the rad and start the engine, is the water being pumped out of the hose? I have a cunning plan.... Will try this, also doing the same with the manifold to heater hose. Heater hose when cold, (it's also the pump bypass), then when warmed and thermostat open (hopefully) the top hose. Then wiring a override switch for the fans, which aren't switching on. Then try it with rad shroud and fans removed, to see if the (possibly) reduced airflow through the rad is the cause. Although I think at even 30 mph the airflow through the rad and shroud should overcome the restriction of the shroud and fans. If I have a spare thermostat gasket, I'll try it without the thermostat too. Maybe after I test top hose flow? |
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Nov 30, 2023 19:46:43 GMT
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I think you will need the thermostat out to check the top hose flow anyway.
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andyborris
Posted a lot
Freedom is just another word for nothing left to lose.
Posts: 2,220
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Nov 30, 2023 20:06:48 GMT
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Could it get worse, my RR is playing up now, getting a error page when I try to post, but it posts anyway.
Which is why I've posted the same thing 3 times, it keeps telling me "the page can't be found" or something similar!
First the Landy, now RR is making me feel like an idiot!
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Nov 30, 2023 22:03:11 GMT
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As mentioned above based on what you have said I would suspect the water pump, i've seen impellors both plastic and metal crack and fail so that they spin a bit but at higher speeds they slip and cause overheating.
I would start with this and then look at other issues, if its overheating in this weather then there is something significantly wrong with it.
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zeberdee
Club Retro Rides Member
Posts: 1,041 
Club RR Member Number: 2
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Just be aware ,
Running without a stat can cause overheating , the water flows unrestricted & doesn’t have time to draw the heat from the engine or stay in the rad long enough to dissipate the heat .
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Last Edit: Dec 1, 2023 9:09:55 GMT by zeberdee
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andyborris
Posted a lot
Freedom is just another word for nothing left to lose.
Posts: 2,220
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As mentioned above based on what you have said I would suspect the water pump, i've seen impellors both plastic and metal crack and fail so that they spin a bit but at higher speeds they slip and cause overheating. I would start with this and then look at other issues, if its overheating in this weather then there is something significantly wrong with it. I think I'm going to take your advice and remove the pump. Usually I have bad luck ( was told that if I didn't have bad luck, I'd have no luck at all, which is true!), so I might get lucky and it's the pump not pumping. When the pump was out to change the camshaft, I looked at it and it looked fine, I even checked if it spun smoothly. Didn't check if the impeller was loose though. Got to look at why the fans aren't switching on too and that'll be easier with the rad out when I change the pump. However, I think this'll be the last money I'll spend chasing this......anyone got a 2.25 petrol for sale? They run for ever!  |
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andyborris
Posted a lot
Freedom is just another word for nothing left to lose.
Posts: 2,220
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Wondering if a slightly (and I mean very slightly!) ovalized bottom hose could hold up the water flow enough to cause overheating.
It did seem that as soon as the engine warmed enough to open the thermostat, it boiled. This took about 10 minutes, took a while for the engine to stay running from cold.
on the previous engine, it overheated almost immediately, as soon as the exhaust got into the coolant.
I'm now thinking that something is stopping the flow of water through the engine, i.e. water pump, kinked hose or even a blocked rad.
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I think we still have a good 3 main bearing 2.25 petrol, I would need to double check it's still there though if you do get desperate. Ran really nicely when removed 20 years ago and has been dry stored since (unless it's been scrapped)
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andyborris
Posted a lot
Freedom is just another word for nothing left to lose.
Posts: 2,220
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I think we still have a good 3 main bearing 2.25 petrol, I would need to double check it's still there though if you do get desperate. Ran really nicely when removed 20 years ago and has been dry stored since (unless it's been scrapped) Hold that thought! I'm going to try again with this engine for a little while longer, got the water pump off yesterday, but haven't had a good look at it yet. Will post photos. Will alter the bottom hose slightly to remove the tiny kink in it and then give it another go. I may be PMing you soon! |
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jimi
Club Retro Rides Member
Posts: 2,224
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May not be in anyway related, but worth mentioning I think. I remember some people having overheating problems when fitting V6 3VZFE engines to MR2's, while others had no problems. Turned out to be down to some aftermarket water pumps having a different impeller design and basically not moving enough water at slower rpm. EDIT found a pic and some info  Pump on the left is a Blueprint pump (uses the same design as a genuine Toyota pump) pump on the right is QH (different design of impeller) The QH pump caused overheating problems, which disappeared after fitting the Blueprint one. This was confirmed by several MR2 engine swappers. As I said may not be relevant, but may be worth considering if a new water pump has been fitted. |
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Last Edit: Dec 2, 2023 16:52:11 GMT by jimi
Black is not a colour ! .... Its the absence of colour
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andyborris
Posted a lot
Freedom is just another word for nothing left to lose.
Posts: 2,220
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Pictures of the water pump. Pump was in engine when I got it.   Could it be the original pump because it was fitted with just sealant, no gasket? Anyway, as far as I could tell, it seems fine. No play on the shaft, impeller seems attached. Did find a drop of coolant in the weep hole, but I think that's from removal. So apart from what Jimi says above, I'm thinking it's not the problem. And with reference to what Jimi says, does the pump look like a problem design? |
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May not be in anyway related, but worth mentioning I think. I remember some people having overheating problems when fitting V6 3VZFE engines to MR2's, while others had no problems. Turned out to be down to some aftermarket water pumps having a different impeller design and basically not moving enough water at slower rpm. EDIT found a pic and some info Pump on the left is a Blueprint pump (uses the same design as a genuine Toyota pump) pump on the right is QH (different design of impeller) The QH pump caused overheating problems, which disappeared after fitting the Blueprint one. This was confirmed by several MR2 engine swappers. As I said may not be relevant, but may be worth considering if a new water pump has been fitted. That was how they cured the Triumph stag's notorious overheating problem by adding more vanes. |
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Pictures of the water pump. Pump was in engine when I got it. Could it be the original pump because it was fitted with just sealant, no gasket? Anyway, as far as I could tell, it seems fine. No play on the shaft, impeller seems attached. Did find a drop of coolant in the weep hole, but I think that's from removal. So apart from what Jimi says above, I'm thinking it's not the problem. And with reference to what Jimi says, does the pump look like a problem design? That's a counterclockwise pump, so the next question is. Which way is the pump turned on the engine by the belt? Is it inside the belt run or outside? |
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andyborris
Posted a lot
Freedom is just another word for nothing left to lose.
Posts: 2,220
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[/quote] That's a counterclockwise pump, so the next question is. Which way is the pump turned on the engine by the belt? Is it inside the belt run or outside?[/quote] It's a multi vee ribbed belt and the pump is on the outside (flat side). The engine is a 3.9 Interim SERPS engine, the one with a ribbed belt and a distributor. The pre SERP water pump looks very different and I've been told it's impossible to fit to a SERPS engine. The layout is the same as this, but without all the air con/power steer gubbins on the right of the picture.  It doesn't seem to slip when revved and others have used this install successfully in (mainly) 7 type cars. Tensioner is new and very tight, need a ratchet strap to loosen it. |
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andyborris
Posted a lot
Freedom is just another word for nothing left to lose.
Posts: 2,220
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Should add that the alternator sits much further to the right, almost over the water pump and more of the belt is in contact with the water pump pulley.
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That's a counterclockwise pump, so the next question is. Which way is the pump turned on the engine by the belt? Is it inside the belt run or outside?[/quote] It's a multi vee ribbed belt and the pump is on the outside (flat side). The engine is a 3.9 Interim SERPS engine, the one with a ribbed belt and a distributor. The pre SERP water pump looks very different and I've been impossible to fit to a SERPS engine. The layout is the same as this, but without all the air con/power steer gubbins on the right of the picture. It doesn't seem to slip when revved and others have used this install successfully in (mainly) 7 type cars. Tensioner is new and very tight, need a ratchet strap to loosen it. [/quote] Well that all looks OK, it's satisfied my line of thought anyway. |
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Dec 13, 2023 23:22:40 GMT
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other thoughts.
What inlet manifold are you running and do the coolant ports line up ok with the heads.
Is the heater circuit plumbed in and open(this is the bypass on RV8's).
Thermostat is the right way round?
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Good shout on the manifold. I seem to recall that some of the aftermarket manifolds need a small hole drilling in the vicinity of the thermostat housing ( can't remember the exact details) to prevent air locks.
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Proton Jumbuck-deceased :-(
2005 Kia Sorento the parts hauling heap
V8 Humber Hawk
1948 Standard12 pickup SOLD
1953 Pop build (wifey's BIVA build).
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Just re read the plumbing route, the heater gets hot water from the back of the inlet manifold and is returned via the pipe underneath it to the water pump inlet not the top hose. As someone else said it's the bypass.
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