13 replies to this topic

[coyttl]

Hey guys, thought I'd get other thoughts on this.. I searched but didn't see anything previously posted.

My '92 SPi always ran cold, ever since owning it. The previous owner said, "It's always been like that." Well, this winter, sick of freezing in my car, I decided to replace the thermostat.

That simple job took MUCH longer than expected. Seems that the original thermostat was still in the housing. The bolts had never been removed, so one was rusted to the housing. (Not the engine block, thanks!) So, I went ahead and ordered a new housing and sandwich plate for the heater hose, new thermostat, gaskets and bolts. The old thermostat was in fact stuck partially open, so it was tossed.

Got all the parts in, reassembled everything. First oddity was that the bolts were too long - each one needed two or three additional washers to tighten down correctly. I thought I got the right bolts (These are the ones I ordered) but am wondering if I err'd. I'd lioke to get the correct ones, if anyone knows the correct part #, it'd be appreciated. If those ARE the right bolts, then I'm puzzled.

Anyways, back to the cooling. While the fluid was low, I looked in the radiator, and do know that it needs a flush, badly. However, it did not get one at this time. I'm glad I didn't - the engine STILL runs cold. (Yes, I checked the thermostat before putting it in - it was good. ) I *think* that the heater gets warm, not sure how warm however. (My Mini has several air leaks, so cold air from outside is mixed with the air from the heater..) Normally, the temp gauge sits just below the "C" line. Since before and after replacing the thermostat, it may rise as high as the "C" line, no higher. It did rise up once to the mid-way point, about 5 months ago while the car was sitting idle, however, have been unable to replicate that since.

I'm thinking I need a new temp sender - anyone have a picture of where it's located? Any other items to check would be appreciated as well. I don't like freezing in the mornings.

Cheers,
Mike.

[Dan]

In your SPi the temperature sender is mounted to the inlet manifold. The injection temp senders are unrelible, it could well be that. Have you actually had a feel of the hoses with the engine running to see if it is heating up?

Moved to the injection section.

[coyttl]

Hey Dan - thanks for moving it, forgot that there was a injection-specific place.

Don't know about the hoses, I honestly forgot to check. I'll check tomorrow and let you know. If they're NOT hot, what else could it be? (As I figure, if they're not hot, then... my engine just runs ... really cool?)

As a side, this is the right sender for an SPi, yes? http://minispares.co....aspx?pid=34159 Took me a while to dig down and find it..

Cheers,
Mike.

[BoyracerAU]

Okay I'm new with SPI and all that goes on with them, but I'm going to hazard a guess that your car wouldn't run properly if it was running cold. I'm guessing it's not the sender but possibly the gauge that's stuffed?

As for the heater, I'm thinking your heater tap could be where it's at. Once the car is warmed up, touch the hose going into the tap and the hose going out of the tap. If one is hot and one is cold (and your tap is open), then there's a blockage or the tap has had it.

[DaveRob]

Make sure the themostat is in the top of the housing and not the head.... this is major important. Their is a thread describing what happens and Sproket made a detailed description which I paste here with credit to Sproket

' the thermostat generates a restriction against the water pump, pressure is built up behind the thermostat. If the heater take off is after the thermostat, there isnt such a big presure difference (it alsmost the same potential as the suction of the pump) to push the coolant through another fairly large restriction that is the heater matrix, the result is very little if any flow. Taking the coolant off before the thermostat, you have the biggest pressure difference, forcing the coolant through the heater matrix and back to the suction of the pump.

This 'restriction' (the thermostat) also increases the boil over temperature of the coolant in the block and head only as a result of the increased pressure generated by the pump. This is the reason it is BAD to remove the thermostat and not fit a blanking sleave in its place.'

The temp sender is an important part of the system and do fail so worth changing but the difference in heat from having the stat in the head to having it at the top of the stat housing is enormous.

Just my thoughts

[coyttl]

Yeah, I placed the thermostat back where the old one came from - on the top of the sandwich housing plate and bottom of the top housing. I also verified that the "direction of flow" was correct for the thermostat - up through the head to the radiator.

Drove it 100 miles round trip yesterday. I'm guessing that now, either my gauge is bad, or the sender's bad.

When cold, the needles quite a bit below the "C" line. As the car warms up, it gets to the "C" line, and pretty much stops. The "amount" of travel is the same as about from the "C" line to halfway to the center line on the gauge.

The hoses did get rather hot, and feeling the air coming directly out of the heater box, the air was hot, so I'm pretty sure the engine's now warming up like it's supposed to. The reason I wasn't able to feel it before was because I have a huge air-leak behind my dash air hoses that I need to figure out.

Thanks guys, next step is to get a new temp sender.

[BoyracerAU]

Mike, I could be wrong, but from what I understand, the SPI's rely heavily on the CTS for information and this has a great impact on how the ECU dictates fueling & spark.

If the car is running okay, then I'm guessing your CTS is okay and it's just your gauge (or the wire that runs between the gauge and the ECU) that's not happening the way it should.

[coyttl]

Thanks Michael.

I don't know how the engine would run differently (although, I may just unplug it and see if there's a difference..) I do know that even before, with the stuck-open thermostat, the engine seemed to run the same. (Only difference was that then, I really had no heat!)

What's odd is that the engine never regularly idles 'high' (like cold engines usually do). Say I rev the engine up, when I release the pedal, it will drop to ~1500 for maybe 5 seconds, then slowly drop to ~800. Does this right when it's fired up, and then, even after a long drive.

So, more poking is necessary, really. I think tomorrow I'll warm him up and then disconnect the sender, just to see if there's an operating difference. That'll rule out the sender one way or another.

Cheers,
Mike.

[coyttl]

Uhm.. okay guys.. Need help. Or a picture. I looked and looked, and couldn't find the temp sender. I only looked on the top of the engine, didn't get underneath. But I didn't and couldn't see it anywhere. I found the oil pressure on the front right of the engine, but no other sender.

I feel kinda silly asking, but couldn't find it.

Thanks guys.

[BoyracerAU]

I haven't seen one of these myself, but IIRC (from other posts I have read), it's in the inlet manifold best reached by taking the radiator out for access.

[Avl_Paul]

You probably need to get hold of a copy of the manual for this one. I haven't removed the CTS yet either but am about to replace mine this week and have read through the Haynes manual. It is mounted on the underside of the intake manifold so you have to drain the coolant, remove the injection unit and and intake manifold! yeah, sounds like a pain in the ass. I would recommend confirming that your CTS is bad by checking the resistance across it using the appropriate pins on the ECU connector (PM me if you need resources for how to do this). I think someone has posted a sticky above about what the correct resistance levels are.

Also, if you don't have a manual yet, you can get the Haynes information on the web. PM me for a locatin.

It looks like you may also be in the States? If so, don't buy the replacement CTS from MM - it is extremely overpriced at > $200. I ended up getting one for around 20 GBP from a shop in England.

[coyttl]

You probably need to get hold of a copy of the manual for this one. I haven't removed the CTS yet either but am about to replace mine this week and have read through the Haynes manual. It is mounted on the underside of the intake manifold so you have to drain the coolant, remove the injection unit and and intake manifold! yeah, sounds like a pain in the ass. I would recommend confirming that your CTS is bad by checking the resistance across it using the appropriate pins on the ECU connector (PM me if you need resources for how to do this). I think someone has posted a sticky above about what the correct resistance levels are.

Also, if you don't have a manual yet, you can get the Haynes information on the web. PM me for a locatin.

It looks like you may also be in the States? If so, don't buy the replacement CTS from MM - it is extremely overpriced at > $200. I ended up getting one for around 20 GBP from a shop in England.

Aw, C**p, so it's not an easy thing to get to. Great.

Hopwever, I think i found my issue. As per this thred, I have the wrong thermostat in the car. Doh. The only other one I have is an 80C/180F, which will go in tonight. We'll see what happens.

[coyttl]

Well, just a quick update.

Put a 91C stat in, and let her warm up. The engine definitely got warmer, according to my temp gauge - now, instead of sitting just north of the blue "C" line, it stops about a needle's width above "C" now. As far as I could tell, the engine performed the same.

(I should also mention that the electric fan has been disconnected this whole time, not running.. So it's not keeping it cold.)

I guess the next step is to measure the resistance of the sender, just to verify it's not the gauge.

Paul - yeah - in the states. Do you know a manufacturer part number for the sender, so if I need to go on a hunt I know what I'm looking at?

Cheers,
Mike.

[BoyracerAU]

Hi Mike,

I was wondering how you went. Did you end up replacing the CTS? Did it make a difference?

As far as I'm aware, the CTS provides info to the ECU and the ECU uses this info to adjust fueling and timing. The ECU also sends info to the temp gauge.

It sounds like your car runs perfectly well, it's just the reading on the temp gauge that seems odd. I'm still inclined to think it's the gauge.

Give us an update. I like reading threads that have a happy ending.