If you are loosing coolant as the car cools and/or after short trips the cause may be the MGF Inlet Manifold Gasket.
Background #
My 1997 MGF 1.8 MPi had started to leave a little pool of coolant on the floor. I noticed that this seemed to happen mostly after a quick start up and shutdown. Like moving the car around in the garage. I thought this was odd. I could take a 1,000 mile trip and not see an issue. Run the car for one minute and shut down, pool of coolant. This went on for about 9 months of me ignoring the issue. Suddenly, the issue got much worse. While the car cooled overnight, I noticed the coolant in the expansion tank dropped about one to one and a half inches! Yikes! You can see the coolant on the back side of the engine block and I could see it started higher than the coolant rail.
Mark Jones had suggested that the problem may be the inlet manifold gasket as soon as I noticed the issue. Naturally, I hoped it was something else, MGF cooling systems are not for the faint of heart. However, I had to face my fears and deal with this.
To help you confirm the symptoms are likely the MGF Inlet Manifold Gasket, there are some searches that will reveal some good discussions. Try a search for “mgf coolant leak back of block“.
Please note this this relates to the regular 120bhp 1.8 MPi version. There are differences with the 143bhp VVC engine.
Great Helpful Resources #
Although I have the workshop manual, I went in search of additional resources. The line drawings are pretty good but I was hoping to find something with pictures.
Tony’s Green Bullet Website #
Doing various web searches I came across a website, Tony’s Green Bullet. Specifically, there was a step-by-step article with pictures. The article seems to mostly follow the workshop manual steps. However, the photos really help with identifying the bits mentioned in the workshop manual. Here’s a link to the Tony’s Green Bullet article on the MGF Inlet Manifold Gasket replacement. There is an extra step in this website that isn’t in the workshop manual. It notes to remove 2 bolts to remove the fuel rail. I didn’t do this but from underneath the car you can see these bolts. Not too bad to find by feel also.
Having Done It Observations #
The workshop manual (see below) is what I followed. I found it fairly easy to understand the steps. Actually doing some of the steps, well, not nearly so easy. Here’s a few observations from following the process.
- The 3 upper manifold nuts are 13mm
- The 4 lower manifold bolts are 10mm
- Getting at the bottom manifold bolts is not easy at all, but experience with doing something like this you cannot see helps. A mixture of extensions will be needed for the socket to have enough length but not too much
- The nut on my fuel filter is 19mm and the fuel line fitting nut is 14mm
- There are some “slip-fit” connections for hoses. That’s how I describe them anyway. The step 8 brake servo line is like that in you hold the red “washer” in place and pull the hose out. Somewhat similar is the fuel filter line to the fuel delivery hose. Press in the plastic connector, and the hose pulls off the hard line
- When refitting the fuel delivery hose to the fuel filter hard line, make sure you hear the connection “click” into place or it will pop apart when you come to turn on the ignition
- The air intake temperature sensor multiplug (step 21) was (a) quite hard to reach and (b) an absolute bugger to disconnect! See the image below of the green connector. I used a screwdriver to press in on the release clip that was facing the engine block to be able to get it to disconnect.
- Mark Jones had suggested getting the “viton” type replacement gasket. I obtained this viton inlet manifold gasket from Rimmer Bros. The part number is LKJ101110.
- Getting a torque wrench in place for the manifold bolts and nuts is quite difficult. For the top nut in the middle of the car, pretty impossible
- The coolant system filling and bleeding turned out to not be as scary as I expected. The workshop manual and a ton of other reading had prepared me
Workshop Manual Extract #
Additional Photos #









Other Materials #
I’ve built this website and spent time on the knowledge base to bring together a lot of information I have collected from around the internet. The intent is making it easy to find rather than having to know about and have skills with search engine query terms to get what you were looking for. Please make use of the knowledge base.